Urs Wenger
(University of Bern)
7/25/16, 9:15 AM
From Spin Models to Lattice QCD – the Scientific Legacy of Peter Hasenfratz
Prof.
Chuan Liu
(Peking University)
7/25/16, 9:45 AM
I review the recent lattice results on spectroscopy and resonances in the past years.
For the conventional hadron spectrum computations,
focus has been put on the isospin breaking effects, QED effects, and simulations near the
physical point. I then go through several single-channel scattering studies
using Luescher formalism which has matured over the past years.
The topics cover light...
Dr
David Wilson
(University of Cambridge)
7/25/16, 10:30 AM
Excited states in hadron physics are seen as resonances in the scattering of lighter stable hadrons like $\pi$, $K$ and $\eta$. Many decay into multiple final states necessitating coupled-channel analyses. Recently it has become possible to obtain coupled-channel scattering amplitudes from lattice QCD. Using large diverse bases of operators it is possible to obtain reliable finite volume...
Prof.
Hartmut Wittig
(University of Mainz)
7/25/16, 11:30 AM
The overall accuracy of the Standard Model prediction of the anomalous
magnetic moment of the muon is currently limited by hadronic
effects. I review the status of lattice QCD calculations, aimed at
providing precise estimates for the hadronic vacuum polarisation and
hadronic light-by-light scattering contributions, respectively. In the
case of the leading hadronic vacuum polarisation...
Sergei Dubovsky
(NYU)
7/25/16, 12:15 PM
I will review recent advances in describing the dynamics of the QCD string (confining flux tube) both on theoretical and on lattice sides. I will argue that combined efforts of theorists and lattice practitioners may result in a dramatic progress in our understanding of the world sheet theory of the QCD string in the nearest future.
Dr
Stephan Durr
(University of Wuppertal)
7/25/16, 2:15 PM
First experiences are reported with overlap fermions which employ the Brillouin action as a kernel. After discussing the dispersion relations of both the kernel and the resulting chiral action, some of the physics features are addressed on quenched backgrounds. We find that the overlap with Brillouin kernel is much better localized than the overlap with Wilson kernel. Also a preliminary...
Dr
Renwick J. Hudspith
(York University)
7/25/16, 2:15 PM
We present results of the hadron spectrum using $n_f=2+1$ ensembles with pion masses as low as 156(4) MeV, we place particular emphasis on measurements of the singly and doubly heavy charm and bottom baryons.
Using the Tsukuba tuning for relativistic charm and NRQCD for the bottom quarks we perform measurements of both light and heavy mesons as well as spin-1/2 and spin-3/2 baryons for all...
Dr
Christian Wiese
(NIC - DESY Zeuthen)
7/25/16, 2:15 PM
Although parton distribution functions are the fundamental objects describing the inner structure of hadrons, they were so far not calculated from first principles.
In the past, lattice QCD has successfully been employed for the computation of hadronic spectra and form factors. Yet calculations of quark distributions are still missing, since they are given by light-cone correlation functions...
Dr
Wolfgang Bietenholz
(UNAM, Mexico)
7/25/16, 2:15 PM
In simulations of a model with topological sectors,
algorithms which proceed in small update steps
tend to get stuck in one sector, especially on fine
lattices. This distorts the numerical results; in
particular it is not straightforward to measure the
topological susceptibility chi_t.
Here we test a method to measure chi_t even if configurations
from only one sector are available....
Kalman Szabo
(U Wuppertal, FZ Juelich)
7/25/16, 2:15 PM
Finite temperature lattice QCD is investigated with four flavor physical mass staggered quarks using lattices upto N_t=20. Results for the equation of state and the low-lying modes of the Dirac-operator are presented with a focus on lattice artefacts.
Dr
Julien Frison
(KEK Theory Center)
7/25/16, 2:35 PM
On the lattice, many definitions of the topological charge $Q$ coexist, and can give very different numbers on a given configuration.
Those definitions will only converge when one takes the continuum limit of the moments $\langle Q^n\rangle$ (provided that $Q$ has been correctly renormalised).
Additionally, other complications arise when one wants to study the mass dependence of the...
Dr
Anthony Francis
(York University)
7/25/16, 2:35 PM
Having introduced the ensembles and basic spectrum in Part I, we focus on results for a doubly heavy tetraquark candidate, $qq\bar Q \bar Q$. Based on phenomenological observations regarding heavy baryon systems, we motivate two possible lattice interpolating operators: a diquark-anti diquark and a meson-meson. We show these operators exhibit good behaviour both in terms of lattice QCD and...
Prof.
Anna Hasenfratz
(University of Colorado)
7/25/16, 2:35 PM
We construct a prototype BSM model where the Higgs boson is a pseudo
Nambu-Goldstone boson by combining 4 light (massless) flavors and 8
heavy flavors. In the infrared, the SU(4) chiral symmetry is spontaneously broken , while in the ultraviolet it exhibits the properties of the $N_f=12$ conformal fixed point. The running coupling of this system ``walks" and the energy range of walking can...
Dr
YIBO Yang
(university of Kentucky)
7/25/16, 2:35 PM
I shall report on the progress of the proton spin decomposition based on Ji’s scheme and also the necessary perturbative calculation, to convert them from the lattice regularization to MS-bar scheme at 2 GeV.
Dr
Johannes Heinrich Weber
(Technische Universität München)
7/25/16, 2:35 PM
I discuss QCD with Flavored Minimally Doubled Fermions as sea quarks.
Minimally Doubled Fermions are an ultra-local formulation that realizes a non-singlet chiral symmetry with only two real fermions at finite lattice cutoff, but break the hypercubic symmetry as well as some discrete space-time symmetries.
I show that the broken discrete space-time symmetries do not affect vacuum since the...
Prof.
Sandor Katz Katz
(Eotvos University, Budapest)
7/25/16, 2:35 PM
We study the QCD transition with dynamical overlap fermions. A continuum extrapolation is carried out using lattices up to N_t=12. We use a fixed topology approach and study its effect on our observables.
Zhaofeng LIU
(Institute of High Energy Physics, Chinese Academy of Sciences, Beijing)
7/25/16, 2:55 PM
Using 2+1-flavor domain wall fermion configurations, we calculate the overlap quark propagator in the Landau gauge. Then we try to extract the chiral condensate from the operator product expansion of the quark propagator in momentum space.
Prof.
Shailesh Chandrasekharan
(Duke University)
7/25/16, 2:55 PM
In this talk we argue that the fermion bag formulation extends the concepts of topology and index theorems associated with non-Abelian gauge theories, to simple lattice fermion field theories. Through such a connection we learn that fermion masses can arise in at least two different ways:(1) a conventional way where some lattice symmetry of the action is spontaneously, explicitly or...
Mr
Gavin Cheung
(University of Cambridge)
7/25/16, 2:55 PM
We present searches for tetraquarks in lattice QCD with quark content $cc\bar{q}\bar{q}$ and isospin-1 $c\bar{c}q\bar{q}$ which are especially of relevance to the experimentally observed charged $Z_c$ states. Utilising the variational method, we employ a large bases of operators consisting of diquark-antidiquark and meson-meson operators. We show the spectra determined across a range of...
Michael Engelhardt
(New Mexico State University)
7/25/16, 2:55 PM
Quark orbital angular momentum (OAM) in the nucleon can be evaluated
directly by employing a Wigner function embodying the simultaneous
distribution of parton transverse position and momentum. This
distribution can be accessed via a generalization of the nucleon
matrix elements of quark bilocal operators which have been used
previously in the lattice evaluation of transverse...
Prof.
Claudio Rebbi
(Boston University)
7/25/16, 2:55 PM
We present our results for the spectrum and other observables of an
SU(3) gauge theory with 4 light fermions and 8 fermions of heavier mass,
built on an IR fixed point. Our numerical data validate hyperscaling
and, while our model does not presume to be a complete theory of EW
symmetry breaking, it exhibits many of the features that would be
expected of a realistic theory where the...
Dr
Szabolcs Borsanyi
(University of Wuppertal)
7/25/16, 2:55 PM
We give a lattice-based description of QCD thermodynamics in the
hadronic phase from staggered simulations of up to $N_t=16$.
Using generalized quark number susceptibilities
we obtain the free energy in various strangeness sectors and
compare it with the expectations from the hadron resonance gas
model. We use the findings to disambiguate between various
spectrum tables. Thus we...
Dr
Philippe de Forcrand
(ETH Zurich & CERN)
7/25/16, 3:15 PM
In its lower left corner, the Columbia plot indicates a first-order
finite-temperature phase transition, which turns into a crossover
as the quark masses increase. The locus of quark masses giving a
second-order transition is a feature of continuum QCD, and should
be recovered with any fermion discretization. However, numerical
evidence has been accumulating, disfavoring universality.
We...
Dr
Shoji Hashimoto
(KEK)
7/25/16, 3:15 PM
We calculate the spectral function of the Mobius domain-wall Dirac operator utilizing a stochastic eigenvalue counting technique. From the low-end of the spectrum we extract the chiral condensate in 2+1-flavor QCD, and take the chiral and continuum limits. Lattice ensembles are those generated with Mobius domain-wall fermions at a~0.080, 0.055 and 0.044 fm.
Prof.
Pedro Bicudo
(Universidade de Lisboa)
7/25/16, 3:15 PM
In previous works we predicted the existence of a $\bar{b} \bar{b} u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ using the static approximation for the $\bar{b}$ quarks and neglecting heavy spin effects. Since the binding energy is of the same order as expected for these heavy spin effects, it is essential to include them in the computation. Here we present a corresponding method and...
Dr
Simon Mages
(Forschungszentrum Jülich)
7/25/16, 3:15 PM
A common problem in lattice QCD simulations on the torus is the extremely long autocorrelation time of the topological charge, when one approaches the continuum limit. The reason is the suppressed tunneling between topological sectors. The problem can be addressed by replacing the torus with a different manifold. Here we propose to use a non-orientable manifold, and show how to define and...
Prof.
Julius Kuti
(U.C. San Diego)
7/25/16, 3:15 PM
Based on recent analysis of the LatHC collaboration I will review critical features of a minimal composite Higgs model close to the conformal window. Challenging problems of the near-conformal paradigm will be compared with PNGB based partial compositeness.
Prof.
Constantia Alexandrou
(University of Cyprus and The Cyprus Institute)
7/25/16, 3:15 PM
The quark contributions to the spin and mass of the nucleon are computed using $N_f=2$ twisted mass fermions with a physical value of the pion mass. We use improved methods to obtain accurate results for
the disconnected contributions involved in the evaluation of the axial charge and quark momentum fraction as well as the light, the strange and the charm $\sigma$-terms.
Dr
Yoshifumi Nakamura
(RIKEN)
7/25/16, 3:35 PM
We investigate the critical endline of the finite temperature phase transition of QCD around the SU(3)-flavor symmetric point at zero chemical potential.
We employ the renormalization-group improved Iwasaki gauge action and non-perturbatively $O(a)$-improved Wilson-clover fermion action.
The critical endline is determined by using the intersection point of kurtosis, employing the...
Dr
Balint Toth
(Bergische Universität Wuppertal)
7/25/16, 3:35 PM
A common problem in lattice QCD simulations on the torus is the extremely long autocorrelation time of the topological charge, when one approaches the continuum limit. The reason is the suppressed tunneling between topological sectors. The problem can be addressed by replacing the torus with a different manifold. Here we propose to use a non-orientable manifold, and show how to define and...
Ms
Antje Peters
(Goethe-Universität Frankfurt am Main)
7/25/16, 3:35 PM
We study $\bar{b} \bar{b} u d$ and $\bar{b} b u \bar{d}$ four-quark systems using lattice QCD. The heavy b quarks are treated either in the static approximation or by using NRQCD. Both for $\bar{b} \bar{b} u d$ (quantum numbers $I(J^P) = 0(1^+)$) and for $\bar{b} b u \bar{d}$ (quantum numbers of $Z_b$, $I(J^P) = 1(1^+)$) our results indicate the existence of a four-quark bound state, i.e. a tetraquark.
Dr
Georg Bergner
(AEC ITP University of Bern)
7/25/16, 3:35 PM
In this work I will summarize our results concerning the spectrum and
mass anomalous dimension of SU(2) gauge theories with a different number
of fermions in the adjoint representation, where each Majorana fermion
corresponds effectively to half a Dirac flavour $N_f$. The most relevant
examples for the extensions of the standard model are supersymmetric
Yang-Mills theory ($N_f=1/2$) and...
Dr
Christian Hoelbling
(Wuppertal University)
7/25/16, 3:35 PM
We construct domain wall fermion operators with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude compared to standard domain wall fermions.
Dr
James Zanotti
(University of Adelaide)
7/25/16, 3:35 PM
Fourier transforms of electromagnetic form factors provide valuable insights into the spatial distribution of quarks/charge within a hadron. When combined with form factors arising from non-forward matrix elements of the tensor operator, we are able to unlock fascinating information into the distribution of transversely polarised/unpolarised quarks within a transversely polarised/unpolarised...
Sergey Syritsyn
(Jefferson Lab)
7/25/16, 3:55 PM
In typical nucleon structure calculations on a lattice, the interpolating fields are optimized to overlap with the nucleon ground state at rest, which in practice limits the momentum transfer in form factors to $Q^2\le 1\,GeV^2$. There is great interest in studying nucleon form factors up to few tens of GeV^2. New experiments at the JLab 12-GeV upgrade will measure nucleon form factors with...
Dr
Ed Bennett
(Swansea University)
7/25/16, 3:55 PM
Motivated by tentative signals of new physics at the LHC, which seems to imply the presence of large mass hierarchies, we investigate the theoretical possibility that these could arise dynamically in new strongly-coupled gauge theories extending the standard model of particle physics. To this purpose, we study lattice data on non-Abelian gauge theories in the (near-)conformal...
Arata Yamamoto
(University of Tokyo)
7/25/16, 3:55 PM
The Berry curvature is a fundamental concept describing topological order of quantum systems.
While it can be analytically tractable in non-interacting systems, numerical simulations are necessary in interacting systems.
We present a formulation to calculate the Berry curvature in lattice QCD.
Edwin Laermann
(Bielefeld University)
7/25/16, 3:55 PM
We present recent results for QCD at non-vanishing chemical potentials for baryon number, electric charge and strangeness.
The results are obtained from Taylor expanding the QCD partition function up to sixth order in these potentials.
The numerical simulations for two light and one strange quark have been carried out on the basis of the Highly Improved Staggered Quark (HISQ) discretization...
Mr
Ryutaro Fukuda
(University of Tokyo, RIKEN BNL Research Center)
7/25/16, 3:55 PM
In recent years, exotic hadrons called X, Y, Z
which cannot be explained by the quark model have been found one after another.
For example, the tetraquark state, which is one of the typical scenarios to interpret the exotic state, is based on the existence of a diquark state.
The discovery of a pentaquark state at CERN in July last year
also makes a diquark state even more important.
It is...
Jacek Wosiek
(Jagellonian University)
7/25/16, 4:45 PM
A positive representation for an arbitrary complex, gaussian weight is derived and used to construct a statistical formulation of gaussian path integrals directly in the Minkowski time.
The positivity of Minkowski weights is achieved by doubling the number of real variables. The continuum limit of the new representation exists only if some of the additional couplings tend to infinity and...
Mr
Joshua Berlin
(University of Frankfurt)
7/25/16, 4:45 PM
To investigate the light scalar tetraquark candidate $a_0(980)$ (quantum numbers $J^P=0^+$), a correlation matrix including a variety of two- and four-quark interpolating operators has to be computed. We discuss efficient techniques to compute the elements of this correlation matrix. In particular we present numerical results for diagrams with closed quark loops and present evidence that such...
Prof.
Stefan Sint
(Trinity College Dublin)
7/25/16, 4:45 PM
A collaborative effort to determine the $\Lambda$-parameter in 3-flavour QCD by the ALPHA collaboration is currently being finalized. The strategy involves 2 finite volume schemes for the coupling, both defined with Schroedinger functional (SF) boundary conditions. I here discuss the scale evolution from an intermediate scale $1/L_0$ of about 4 GeV to scales of O(100) GeV using the...
Dr
Tanmoy Bhattacharya
(Los Alamos National Laboratory)
7/25/16, 4:45 PM
The quark chromo-electric dipole moment operator and the pseudo-scalar fermion bilinear with which it mixes under renormalization can both be included in a calculation of the electromagnetic form factor of the nucleon using the Schwinger source method. A preliminary calculation of these operators using clover quarks on HISQ lattices generated by MILC collaboration will be presented showing...
Mr
Christopher Czaban
(Goethe University Frankfurt am Main)
7/25/16, 4:45 PM
QCD at zero baryon density in the limit of infinite quark mass undergoes a first order deconfinement phase transition at a critical temperature T_c corresponding to the breaking of the global centre symmetry.
In the presence of dynamical quarks the global centre symmetry is explicitly broken. Lowering the quark mass the first order phase transition weakens and terminates in a second order...
Dr
Yigal Shamir
(Tel Aviv University)
7/25/16, 5:05 PM
Recent simulations suggest the existence of a very light singlet scalar
in QCD-like theories that may be lying just outside the conformal window.
Assuming that the lightness of this scalar can be explained by an
approximate dilatation symmetry, we develop an effective field theory
framework for both the pions and this light scalar, the "dilatonic meson."
We argue that a power counting...
Mr
Alexander Chambers
(University of Adelaide)
7/25/16, 5:05 PM
Although hadron structure calculations in lattice QCD
have improved greatly in recent years,
many problems still remain.
Various techniques for determining fermion line disconnected contributions to
matrix elements have produced exciting and promising results, but
rely on complicated analyses.
Additionally, calculations of electromagnetic form factors at high
momentum transfers remain...
Mr
Hikaru Kawauchi
(Kanazawa University)
7/25/16, 5:05 PM
We investigate the phase structure of the lattice CP(N-1) model in two dimensions by using the tensor renormalization group (TRG) method. The TRG method has no sign problem even though the action is complex. We focus on the case N=2 and compare the numerical result of the TRG method with that of the strong-coupling analysis in the presence of the theta term.
Mr
Alessandro Sciarra
(Goethe Universität)
7/25/16, 5:05 PM
The QCD phase diagram at imaginary chemical potential exhibits a rich structure and studying it
can constrain the phase diagram at real values of the chemical potential. Moreover, at imaginary
chemical potential standard numeric techniques based on importance sampling can be applied, since
no sign problem is present.
In the last decade, a first understanding of the QCD phase diagram at...
Dr
Jacob Finkenrath
(german)
7/25/16, 5:05 PM
We present an alternative method to the Generalized Eigenvalue Problem (GEVP) for extracting excited states.
The method is based on statistically sampling the space of possible set of parameters according to the $\chi^2$-value of each set of values.
This method is particularly suited when one has noisy data as is the case for some correlators at large times
such as in the scalar light qqbar...
Mr
Tobias Neitzel
(Goethe University Frankfurt)
7/25/16, 5:25 PM
We present a method for computing the static quark-antiquark potential,
which is not based on Wilson loops, but where the trial states are
formed by eigenvector components of the covariant Laplace operator. We
have tested this method in SU(2) Yang-Mills theory and obtained results
with statistical errors of similar magnitude compared to a standard
Wilson loop computation. The runtime of...
Prof.
Maarten Golterman
(San Francisco State University)
7/25/16, 5:25 PM
We consider applications of a recently developed effective field theory
for a dilatonic meson and pions. We contrast the leading-order behavior
of masses with that in a theory with only pions, comment on
next-to-leading order, and argue that the effective theory breaks down at
the sill of the conformal window, as it should.
Prof.
Rainer Sommer
(NIC @ DESY)
7/25/16, 5:25 PM
The ALPHA-collaboration computation
of the three-flavor Lambda-parameter and the determination of $\alpha(m_Z)$
consists of the steps:
Running from beyond the Z-mass to 4 GeV in the SF scheme,
matching to the GF scheme,
running from 4GeV to small energy in the GF scheme,
determining the smallest energy scale ($\approx$ 200 MeV) in
physical units with the help of the CLS...
Ms
Francesca Cuteri
(Goethe University - Frankfurt)
7/25/16, 5:25 PM
The attempt at clarifying the order of the thermal transition in the chiral limit of QCD at zero chemical potential, with two dynamical flavours of quarks, by progressively decreasing the simulated pion mass has proven to be inconclusive because of the increasing costs of the simulations as the pion mass is lowered.
An alternative way to approach this question is to consider the path...
Stefan Kühn
(Max Planck Institute of Quantum Optics)
7/25/16, 5:25 PM
During recent years there has been quite some interest in applying Matrix Product States and more general tensor networks to lattice gauge theories in the Hamiltonian formulation. Previous work already demonstrated the power of this approach by computing the mass spectrum and thermal sates for the Schwinger model, and also real-time dynamics for abelian and non-abelian gauge models have been...
Ms
Tugba Buyukbese
(University of Sussex)
7/25/16, 5:45 PM
Recently, new four-dimensional (gauge-Yukawa) theories have been discovered which
display exact interacting fixed points at highest energies. In a regime where asymptotic
freedom is lost, these novel types of theories develop an asymptotically safe UV fixed
point, strictly controlled by perturbation theory. In this talk, we extend these studies to include couplings with non-vanishing...
Dr
Eliana Lambrou
(University of Wuppertal)
7/25/16, 5:45 PM
We present preliminary results to determine the strong coupling constant by using the gradient flow. Pure SU(3) gauge theory is studied. We carry out a direct analysis on very fine zero temperature lattices. In addition we attempt to move towards the perturbative regime by using step-scaling.
Dr
Pavel Buividovich
(Regensburg University)
7/25/16, 5:45 PM
I present a Diagrammatic Monte-Carlo algorithm for the large N SU(N)xSU(N) principal chiral model, which stochastically samples planar Feynman diagrams of the lattice perturbation theory. The latter is constructed using the Cayley map from SU(N) group manifold to the space of Hermitian matrices. I demonstrate that the Jacobian of this map results in the massive bare lattice propagator with the...
Prof.
Keh-Fei Liu
(University of Kentucky)
7/25/16, 5:45 PM
I shall report on calculations of isovector matrix elements of the nucleon, such as $g_A, g_s$, and $\langle x \rangle$ on the $48^3 \times 96$ lattice with pion mass at 139 MeV and lattice size of 5.5 fm. We employ overlap valence fermion on the 2+1 flavor DWF configurations for the calculation. Also reported will be the strange quark momentum fraction and its magnetic moment from this...
Dr
Kouji Kashiwa
(Yukawa Institute for Theoretical Physics, Kyoto University)
7/25/16, 5:45 PM
We propose a new determination of the confinement-deconfinement transition by using the imaginary chemical potential. The imaginary chemical potential can be interpreted as the Aharonov-Bohm phase and then an analogy of the topological-order suggests that the Roberge-Weiss endpoint would define the deconfinement temperature. Based on the topological property, we can construct a new quantity...
Prof.
Francesco Knechtli
(University of Wuppertal)
7/25/16, 5:45 PM
Recently the LHCb experiment found evidence for the existence of two
exotic resonances consisting of $c\bar{c}uud$ quarks. Among the possible
interpretations there is the hadro-charmonium model, in which charmonium
is bound "within" a hadron. We test this idea on CLS $n_f$=2+1 lattices
using the static formulation for the heavy quarks. We find that the
static potential is modified by the...
Mr
Ciaran Hughes
(University of Cambridge)
7/25/16, 6:05 PM
Throughout the literature, phenomenological models have been unsuccessful in pinning down the heavy quarkonia hindered M1 radiative transitions (i.e., those radiative transitions between states with different principal quantum numbers that require one of the quarks to flip-spin) and yield predictions that are spread over a vast range.
In this talk, we will learn how to accurately and...
Mr
Andrew Bond
(University of Sussex)
7/25/16, 6:05 PM
We will discuss some of the recent developments in understanding ultraviolet completions of gauge-Yukawa theories beyond traditional asymptotic freedom.
Mr
Fabian Hutzler
(University Regensburg)
7/25/16, 6:05 PM
We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using...
Dr
Tobias Hartung
(King's College London)
7/25/16, 6:05 PM
In lattice QFT, we are often presented with integrals over polynomials of coefficients of matrices in $U(N)$ or $SU(N)$ with respect to the Haar measure. In some physical situations, e.g., in presence of a chemical potential, these integrals are, however, numerically very difficult since they are highly oscillatory which manifests itself in form of the sign problem. In these cases, Monte Carlo...
Mr
Ryoichiro Ueno
(Graduate School of Science, Hiroshima University)
7/25/16, 6:05 PM
We calculate the $\Lambda$-parameter in $\overline{\mathrm{MS}}$ scheme for SU(3) pure gauge theory with the twisted gradient flow method non-perturbatively. Using the Schrödinger functional scheme as an intermediate scheme, we numerically evaluate the $\Lambda$-parameter ratio...
Mr
Michele Mesiti
(University of Pisa and INFN - Sezione di Pisa)
7/25/16, 6:05 PM
In this talk I will report on our recent results about the
determination of the position and the nature of the Roberge-Weiss
endpoint. Our study is performed in $N_f=2+1$ QCD, with physical quark
masses, making use of stout-improved staggered fermions and of the
tree level Symanzik...
David Y.-J. Chu
(Department of Electrophysics, National Chaio Tung University)
7/25/16, 6:25 PM
We study the scaling property of Higgs-Yukawa models. Using the technique of Finite-Size Scaling, we are able to derive formulae to describe the behaviour of the observables near the Gaussian fixed point. The renormalisation procedure is discussed in this talk. A feasibility study of our strategy is performed for pure scalar theory. In addition, we test the formulae with lattice data...
Masanori Hanada
(Kyoto U, Stanford U)
7/25/16, 6:25 PM
We argue that a small, quantum black hole can be made from atoms and lasers.
The holographic principle claims that the quantum gravitational systems, e.g. superstring theory, is equivalent to non-gravitational quantum systems, e,g. super Yang-Mills theory. Here the 'equivalence' means two theories cannot be distinguished even in principle. Therefore, if the holographic principle is true,...
Prof.
Christian Fischer
(JLU Giessen)
7/25/16, 6:25 PM
I will give an overview on our recent results for the phase
diagram of QCD with Nf=2+1 and Nf=2+1+1 flavors. We use a combination
of lattice and Dyson-Schwinger methods to determine the chiral
and deconfinement order parameters at finite temperature and chemical
potential. In a recent exploratory study we also give a first estimate
on the influence of baryon effects on the location of...
Mr
Michael Gruber
(RQCD collaboration)
7/25/16, 6:25 PM
Octet baryon distribution amplitudes are non-perturbative objects of phenomenological interest parametrizing the momentum distribution within the corresponding Fock states. Their normalization and their moments can be calculated using lattice QCD, and such results require renormalization. However, the MS-bar scheme, i.e., the renormalization scheme used in phenomenological applications,...
Prof.
Gerrit Schierholz
(DESY)
7/25/16, 6:25 PM
The running coupling constant $\alpha_s(Q^2)$ is computed from the Wilson flow for three quark flavors on multiple volumes and a wide range of lattice spacings, which allows for a continuum extrapolation. Of particular interest is the behavior at small $Q^2$ and the question of an infrared fixed point.
Mr
Cian O'Hara
(Trinity College Dublin)
7/25/16, 6:25 PM
We present preliminary calculations towards radiative transitions in charmonium using Nf = 2+1 dynamical ensembles generated by the Hadron Spectrum Collaboration. A crucial ingredient in this work is the use of variationally optimised interpolating operators which allow for a reliable determination of the three-point correlation functions needed. Using these operators, we perform first...
Dr
Laurent Lellouch
(CNRS & Aix-Marseille U.)
7/25/16, 7:00 PM
The origin of mass is mysterious. In our everyday experience, the mass of an object is the sum of the mass of its parts. However, in the world of subatomic particles such as quarks and gluons, this everyday assumption is no longer true and even very small mass differences can have cosmic consequences. After an introduction to the subatomic world and the mechanisms by which mass emerges, I...
Prof.
Martin Savage
(Institute for Nuclear Theory)
7/26/16, 9:00 AM
Lattice QCD is making good progress toward calculating the structure and properties of light nuclei and the forces between nucleons. These calculations will ultimately
refine the nuclear forces, particularly in the three- and four-nucleon sector and the
short-distance interactions of nucleons with electroweak currents, and allow for a reduction of uncertainties in nuclear many-body...
Dr
Shinji Takeda
(Kanazawa University)
7/26/16, 10:15 AM
In this talk, I will review the recent progress of tensor network approaches;
Hamiltonian/Hilbert-space approach and Lagrangian/path-integral approach,
whose striking feature is free of the sign problem.
As examples, I will show some results of CP(N-1) model including theta-term and other models.
Finally, I will address outstanding problems and discuss future prospects.
Dr
Sara Collins
(University of Regensburg)
7/26/16, 11:15 AM
Recent calculations of hadron structure observables and related
technical and theoretical advances are reviewed. A wealth of
information on the properties of hadrons can be provided by lattice
methods such as their wavefunctions, response to electromagnetic, weak
or beyond the Standard Model probes and their internal dynamics in
terms of the contributions from quarks and gluons. Progress...
Prof.
Huey-Wen Lin
(Michigan State University)
7/26/16, 12:00 PM
Studying the structure of nucleons is not only important to understanding the strong interactions of quarks and gluons, but also to improving the precision of new-physics searches.
Since a broad class of experiments, including the LHC and dark-matter detection, require Standard-Model backgrounds with parton distribution functions (PDFs) as inputs for disentangling SM contributions from...
Dr
Akaki Rusetski
(HISKP, University of Bonn, Germany)
7/26/16, 2:00 PM
We propose a framework for the extraction of the $B\to K^*$ decay form factors from lattice data, based on the non-relativistic effective field theory in a finite volume. A possible admixture of the $\eta K$ channel is studied, and the multi-channel Lellouch-Luescher formula is reproduced. Further, a procedure is
formulated for the extraction of the form-factors at the resonance pole. The...
Christoph Lehner
(BNL)
7/26/16, 2:00 PM
I present our recent results for the disconnected HVP contribution and report the current status of our light connected HVP contribution to the muon anomalous magnetic moment.
Dr
Yu Maezawa
(YITP, Kyoto University)
7/26/16, 2:00 PM
We present new results on the charm and bottom quark masses as well as the strong coupling constant in 2+1-flavor QCD
using Highly Improved Staggered Quark action and gauge configurations generated by HotQCD Collaboration.
Our approach is based on calculating the moments of meson correlators and we use a wide range of lattice spacing up to $a^{-1} \sim 4.9$ GeV in our study.
The ratios of...
Mr
Felipe Attanasio
(Swansea University)
7/26/16, 2:00 PM
Complex Langevin simulations have been able to successfully reproduce results from Monte Carlo methods in the region where the sign problem is mild and make predictions when it is exponentially hard. We present here our study of the QCD phase diagram in the limit of heavy and dense quarks (HDQCD) for 3 different lattice volumes and the boundary between the hadronic phase and the quark-gluon...
Daniel Nogradi
(Eotvos University)
7/26/16, 2:00 PM
Numerical results are reported on the discrete $\beta$-function of $SU(3)$ gauge theory with $N_f=12$ fundamental fermions in the gradient flow scheme. Controlled continuum extrapolation is performed for $s=2\;$ scale change with $c = \sqrt{8t} / L = 0.2$ targeting 3 tuned values of the renormalized coupling, approximately $g^2=6.0,\; 6.2\;$ and $\;6.4$. Contrary to a previous claim, no...
Markus Werner
(University of Bonn)
7/26/16, 2:00 PM
We present new results for $I=1 \ \pi\pi$ scattering with twisted mass fermions utilizing
the sLapH method. The breaking of rotational symmetry on the lattice is fully taken
into account at multiple moving frames. Our previous calculation is
extended by more single and multi-hadron operators and by utilising more
irreducible representations.
Dr
George Fleming
(Yale University)
7/26/16, 2:20 PM
The LSD Collaboration has recently completed a study of the light hadron spectrum in SU(3) gauge theory with eight light, degenerate flavors. We have observed that the lightest isosinglet scalar meson, also called the sigma, remains essentially degenerate with the pions even when the (pi,sigma) multiplet mass scale falls below half the rho meson mass as a function of the input quark mass. ...
Dr
Maxim Mai
(George Washington University)
7/26/16, 2:20 PM
We propose a method for the direct extraction of the complex hadron-hadron optical potential (or, equivalently, the phase shift and inelasticity in a given channel) on the lattice, which does not require the use of the multi-channel Lüscher formalism, but the knowledge of a tower of energy levels only.
The approach works for any multi-particle states and tested explicitly on a set of...
Dr
Krzysztof Cichy
(Goethe-University Frankfurt am Main)
7/26/16, 2:20 PM
We perform a benchmark study of the step scaling procedure for the ratios of renormalization constants extracted from position space correlation functions. We work in the quenched approximation and consider the pseudoscalar, scalar, vector and axial vector bilinears. The pseudoscalar/scalar cases allow us to obtain the non-perturbative running of the quark mass over a wide range of energy...
Dr
Benjamin Jaeger
(Swansea University)
7/26/16, 2:20 PM
Complex Langevin methods have been successfully applied in theories that suffer from a sign problem such as HDQCD. We present and illustrate a novel method that ensures that Complex Langevin simulations stay close to the SU(3) manifold, which lead to correct and improved results in the framework of HDQCD and pure gauge simulations. Applying the same technique in fully dynamical QCD simulations...
Mr
Luchang Jin
(Columbia University)
7/26/16, 2:20 PM
We report our recent lattice calculation of hadronic light-by-light contribution to muon $g-2$ using our recent developed moment method. The connected diagrams and the leading disconnected diagrams are included. The calculation is performed on a $48^3 \times 96$ lattice with physical pion mass and 5.5 fm box size. We expect sizable finite volume and finite lattice spacing corrections to the...
Mr
Bin Hu
(Department of Physics, The George Washington University)
7/26/16, 2:20 PM
The $\rho (770)$ meson is the most extensively studied resonance in lattice QCD
simulations in two ($N_f=2$) and three ($N_f=2+1$) flavors. We
analyze all available phase shifts from $N_f=2$ simulations using unitarized Chiral Perturbation
Theory, allowing not only for the extrapolation in mass but also in flavor,
$N_f=2\rightarrow N_f=3$. The flavor extrapolation requires information from...
Mr
Daniel Robaina
(Institute for Nuclear Physics Mainz)
7/26/16, 2:40 PM
The Generalized Eigenvalue Problem (GEVP) has been intensively used in the past in order to reliably extract energy levels from time-dependent euclidean correlators calculated in Lattice QCD. We propose an alternative formulation of the GEVP in frequency space. Our approach consists in applying the model independent Backus-Gilbert method to a set of euclidean two-point functions with common...
Mr
David Preti
(Instituto de Física Teórica CSIC/UAM)
7/26/16, 2:40 PM
We present our results for the computation of the non-perturbative running
of renormalized quark masses in $N_f=3$ QCD, between the electroweak and
hadronic scales, using standard finite-size scaling techniques. The
computation is carried out to very high precision, using massless
$\mathcal{O}$(a) improved Wilson quarks. Following the strategy adopted by
the ALPHA...
Dr
Nicolas Garron
(PU)
7/26/16, 2:40 PM
We investigate QCD at finite densities of heavy quarks from a density-of-state perspective. Using the LLR approach, we can compute the phase-factor expectation value in the strong sign problem regime with unprecedented precision due to its inherent exponential error suppression.
We use our findings to draw conclusions on the approach using phase cumulants.
Mr
Andrew Gasbarro
(Yale University)
7/26/16, 2:40 PM
In recent years, lattice studies of multi-flavor gauge theories near and inside the conformal window have provided strong evidence for the existence of light 0++ states in their spectra, which has led to a renewed interest in strong dynamics as a solution to the Higgs hierarchy problem. An additional requirement to realize a UV complete composite Higgs sector is that observables of low energy...
Hanno Horch
(University of Mainz)
7/26/16, 2:40 PM
We present results of our lattice QCD study of the hadronic vacuum polarization (HVP)
function with O$(a)$-improved $N_{\rm f}=2$ Wilson fermions with twisted boundary
conditions. We discuss the extraction of the leading order hadronic contribution to the
anomalous magnetic moment of the muon $\left(a_\mu^{\mathrm{HLO}}\right)$ via the
hybrid method involving two steps: (i) To describe...
Mr
Antoni Woss
(University of Cambridge)
7/26/16, 2:40 PM
Distillation is a method of smearing that allows for the efficient computation of correlation functions on the lattice. It vastly reduces the number of operations needed to calculate correlation functions with large bases of operators and all-to-all propagators. In this investigation, we provide a comprehensive comparison of the quality of extracted energy spectra with different amounts of...
Christian Rohrhofer
(University of Graz)
7/26/16, 3:00 PM
We identify the chiral and angular momentum content of the
leading quark-antiquark Fock component for the $\rho(770)$ and
$\rho(1450)$ mesons using a two-flavor lattice simulation with dynamical
Overlap Dirac fermions. We extract this information from the overlap factors
of two interpolating fields with different chiral structure and from the unitary transformation
between chiral and...
Ms
Julia Volmer
(DESY Zeuthen)
7/26/16, 3:00 PM
The error scaling for Markov Chain - Monte Carlo techniques (MC-MC)
with $N$ samples behaves like $\frac{1}{\sqrt{N}}$. This scaling makes
it often very time intensive to reduce the error of calculated
observables, in particular for applications in lattice QCD.
It is therefore highly desirable to have alternative methods at hand
which show an improved error scaling. One candidate for...
Katsumasa Nakayama
(Nagoya University)
7/26/16, 3:00 PM
We extract the charm quark mass and the strong coupling
constant
by using the charmonium current correlators with $n_f$ = 2 + 1 Mobius
domain
wall fermions. The temporal moments of the correlators are sensitive to
short-distance physics, and could be also calculated in the
continuum theory by perturbative expansion, which is known up to four-
loop order.We match our lattice calculation...
Mr
Mario Giuliani
(University of Graz)
7/26/16, 3:00 PM
We study new developments for the Density of States (DoS) method to simulate systems
affected by the complex action problem. In particular we use the functional fit approach
(FFA). It consists of a restricted Monte Carlo simulation with an additional Boltzmann
factor, which allows one to explore the DoS for a given part of the spectrum. We
fit the simulation data with a known function to...
Mr
James Harrison
(University of Southampton)
7/26/16, 3:00 PM
Lattice calculations of the leading-order hadronic contribution to the muon g-2, from the hadronic vacuum polarisation, are approaching sub-percent level precision. At this level, it becomes important to consider corrections from isospin-breaking. Here, we include quenched QED in our simulations by stochastically generating U(1) gauge configurations and combining these with existing SU(3)...
Dr
Savvas Zafeiropoulos
(Goethe University Frankfurt)
7/26/16, 3:20 PM
We study a Random Matrix Model for QCD at finite density via Complex Langevin dynamics. This model has a phase transition to a phase with non-zero baryon density. We study the convergence of the algorithm as a function of the quark mass and the chemical potential and focus on two main observables: the baryon density and the chiral condensate. As expected, for simulations close to the chiral...
Prof.
Ting-Wai Chiu
(National Taiwan University)
7/26/16, 3:20 PM
I present the updated results of the discrete $\beta$-function of the $SU(3)$ gauge theory with $N_f=10$ massless optimal domain-wall fermions in the fundamental representation.
The renormalized coupling is obtained by the finite-volume gradient flow scheme on $ L^4 $ lattices, for seven lattice sizes: $ L/a = 8, 10, 12, 16, 20, 24, 32 $;
and each with $11 - 17$ different lattice spacings...
Dr
Raul Briceno
(Thomas Jefferson National Accelerator Facillity)
7/26/16, 3:20 PM
In this talk, I present recent progress towards the determination of resonant systems via lattice QCD. The truncation of the volume -- necessary for lattice QCD calculations -- significantly alters the analytic structure of the theory. For scattering processes involving two-hadron states, this can be circumvented by utilizing formalism to map finite-volume quantities obtained onto the desired...
Ms
Vera Guelpers
(University of Southampton)
7/26/16, 3:20 PM
We present a strategy to calculate the leading order electromagnetic corrections to meson masses and the hadronic vacuum polarization. These corrections are computed directly through a QED perturbative expansion of the QCD+QED correlation functions. We will show some first results obtained using $N_f=2+1$ Domain Wall fermions. This calculation will be directly compared to the stochastic...
Prof.
Ulli Wolff
(HU Berlin)
7/26/16, 3:20 PM
We study the O(3) sigma model on a D=2 lattice with a Boltzmann weight linearized in $\beta$ on each link.
While the spin formulation now suffers from a sign-problem the equivalent loop model remains positive and
becomes particularly simple. By studying the transfer matrix and by performing MC simulations in the loop form
we study the mass gap coupling in a step scaling analysis. The...
Mr
Lukas Varnhorst
(University of Wuppertal)
7/26/16, 3:20 PM
We present a determination of the corrections to Dashen's theorem and of the individual up and down quark masses from a lattice calculation based on quenched QED and $N_f=2+1$ QCD simulations with 5 lattice spacings down to $0.054 \, \mbox{fm}$. The simulations feature lattice sizes up to $6 \, \mbox{fm}$ and average up-down quark masses all the way down to their physical value. For the...
Doug Toussaint
(University of Arizona)
7/26/16, 3:40 PM
[MILC collaboration}
In QCD simulations at small lattice spacings the topological charge $Q$
evolves very slowly, and if this quantity is not properly equilibrated
it could lead to incorrect results for physical quantities, or incorrect
estimates of their errors. We use the known relation between the dependence
of masses and decay constants on the QCD vacuum angle $\theta$ and...
Mr
Nils Asmussen
(Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
7/26/16, 3:40 PM
The anomalous magnetic moment of the muon currently shows a more than $3\sigma$ discrepancy between the experimental value and recent Standard Model predictions. The theoretical uncertainty is dominated by the hadronic vacuum polarization and the hadronic light-by-light (HLbL) scattering contributions, where the latter has so far only been fully evaluated using different models. To pave the...
Prof.
Stephen Sharpe
(University of Washington)
7/26/16, 3:40 PM
We report progress on extending the relativistic model-independent quantization condition for three particles to a broader class of theories, and in checking the formalism. Topics that will be touched on are: (i) the extension to include the possibility of 2->3 and 3->2 transitions and (ii) checks of the formalism by comparing to threshold expansions and to the energy shift of a three-particle...
Mr
chik him Wong
(University of Wuppertal)
7/26/16, 3:40 PM
We will present results on important spectroscopy problems of the sextet composite Higgs model selected from the light scalar spectrum, vector resonances, the eta’ particle of the axial anomaly, and spectroscopy analysis using a mixed action with restored chiral symmetry of valence fermions.
Prof.
Yannick Meurice
(University of Iowa)
7/26/16, 3:40 PM
We reformulate the Ising model, the O(2) model with a chemical potential and the Abelian Higgs model on a 1+1 space-time lattice using the
Tensor Renormalization Group (TRG) method. The reformulation allows exact blocking and connects smoothly the classical Lagrangian approach to the quantum Hamiltonian approach. We discuss the linearization of the TRG for the Ising model near the critical...
Dr
Donald SInclair
(Argonne-Seville)
7/26/16, 4:30 PM
We simulate Lattice QCD with 2 light quark flavours at zero temperature and finite quark number chemical potential $\mu$. Gauge cooling is applied, along with adaptive rescaling of the updating `time' increment, to stabilize the algorithm. We see evidence for the expected transition at $\mu \approx m_N/3$ and for saturation at large $\mu$. Limitations of the method are discussed.
Dr
Taichi Kawanai
(Forschungszentrum Jülich (Budapest-Marseille-Wuppertal collaboration))
7/26/16, 4:30 PM
Recent phenomenological and lattice determinations of the anomalous magnetic moment of the muon $a_\mu$ hint at beyond the Standard Model physics on the 3-4 sigma level. Here we present lattice results for the leading order hadronic contribution of $a_\mu$ obtained from 2+1+1 flavor, staggered quark simulations at the physical point. The various quark flavor contributions, together with their...
Mr
Christopher Helmes
(HISKP Universität Bonn)
7/26/16, 4:30 PM
We present results for the interaction of two Kaons at maximal
isospin. The calculation is based on 2+1+1 flavour gauge
configurations generated by the ETM Collaboration featuring
pion masses ranging from about 230 MeV to 450 MeV at three
values of the lattice spacing. The elastic scattering length
$a_0$ is calculated at several values of the bare
strange quark and light quark masses....
Ms
Barbara De Palma
(Istituto Nazionale di Fisica Nucleare (INFN) and Università di Pavia)
7/26/16, 4:30 PM
We report lattice simulations of $\phi^4_2$ and $O(N)\,\phi^4$ models, performed by means a Monte Carlo method based on the all-order strong coupling expansion (worm algorithm). The investigation of the non–perturbative features of the $\phi^4$ continuum limit in two dimensions lead us to the result $g/\mu^2 = 11.15 \pm 0.06_{stat} \pm 0.03_{syst}$ for the critical coupling. Furthermore we...
Dr
Syo Kamata
(Keio University)
7/26/16, 4:30 PM
We investigate the two-dimensional $\mathcal{N}=(2,2)$ supersymmetric
Yang-Mills (SYM) theory on the discretized curved space both from theoretical and numerical points of view.
We first show that the number of the supersymmetry of the continuum $\mathcal{N}=(2,2)$ SYM theory on any curved manifold is enhanced to two by considering an appropriate $U(1)$ gauge backgrounds associated with...
Dr
Hidenori Fukaya
(Osaka University)
7/26/16, 4:30 PM
We propose a 6-dimensional lattice regularization of chiral gauge theories.
In our formulation, Weyl fermions are localized on the junction of two
different domain-walls. One domain-wall naturally exhibits the
Stora-Zumino chain of the anomaly descent equations. Another domain-wall mediates a similar inflow of the global anomalies. The anomaly free condition is equivalent to requiring the...
Jozef Dudek
(Jefferson Lab)
7/26/16, 4:50 PM
We present the first calculation of coupled-channel meson-meson scattering in the isospin $=1$, $G$-parity negative sector, with channels $\pi \eta$, $K\overline{K}$ and $\pi \eta'$, in a first-principles approach to QCD. From the discrete spectrum of eigenstates in three volumes extracted from lattice QCD correlation functions we determine the energy dependence of the $S$-matrix, and find...
Dr
Kohtaroh Miura
(Centre de Physique Theorique, Aix-Marseille Universite, BMW Collaboration)
7/26/16, 4:50 PM
The low, euclidean momentum behavior of the hadron vacuum polarization (HVP) is critical for determining, amongst other quantities, the anomalous magnetic moments of the electron and the muon. Here we present lattice QCD results for the first few moments of the HVP obtained from 2+1+1 flavor, staggered-quark simulations at the physical point. The various quark-flavor contributions, together...
Ms
Emilie Huffman
(Duke University)
7/26/16, 4:50 PM
We solve a variety of sign problems for models in lattice field theory using the Hamiltonian formulation, including Yukawa models and simple lattice gauge theories. The solutions emerge naturally in continuous time and use the dual representation for the bosonic fields. These solutions allow us to construct quantum Monte Carlo methods for these problems. The methods could provide an...
Prof.
Gert Aarts
(Swansea University)
7/26/16, 4:50 PM
In the complex Langevin approach to lattice simulations at nonzero density, zeroes of the fermion determinant lead to a meromorphic drift and hence a need to revisit the theoretical justification. In this talk we discuss how poles in the drift affect the formal justification of the approach and then explore the various possibilities in simple models. The implications of the findings for heavy...
Prof.
Joel Giedt
(Rensselaer Polytechnic Institute)
7/26/16, 4:50 PM
Formulations of lattice supersymmetry over the last decade have been able to significantly reduce the amount of fine-tuning necessary in order to obtain the correct continuum limit. In the case of N=4 super Yang-Mills, the approach that has emerged as the best path forward is based on a topological twisting of the theory. Montonen and Olive found evidence that a duality could exist in...
Mr
Ryo Yamamura
(Osaka U.)
7/26/16, 4:50 PM
We propose a 6-dimensional lattice regularization of chiral gauge
theories. In our formulation, Weyl fermions are localized on the
junction of two different domain-walls. One domain-wall naturally
exhibits the Stora-Zumino chain of the anomaly descent equations.
Another domain-wall mediates a similar inflow of the global anomalies.
The anomaly free condition is equivalent to requiring the...
Mr
Alessandro Nada
(Università di Torino & INFN, Torino)
7/26/16, 5:10 PM
Jarzynski's equality is a well-known result in statistical mechanics, relating free-energy differences between equilibrium ensembles with fluctuations in the work performed during non-equilibrium transformations from one ensemble to the other.
In this talk, an extension of this relation to lattice gauge theory will be presented, along with numerical results for the $Z_2$ gauge model in three...
Mr
Jishnu Goswami
(IIT Kanpur)
7/26/16, 5:10 PM
Minimally doubled fermions(MDF) having only two species could be
promising formalism to study chiral fermion on a lattice. The action being ultra-local, one expects that the MDF formulations might provide computationally cheaper
alternatives to the existing lattice chiral formulations. Borici-Creutz fermion is one such
minimally doubled fermion formulation. In this work, we explore the...
Dr
Denes Sexty
(Uni Wuppertal)
7/26/16, 5:10 PM
Lattice QCD at non-vanishing chemical potential is studied using the complex Langevin equation (CLE). We compare the results with multi-parameter reweighting both from μ=0 and phase quenched ensembles. A good agreement is found for lattice spacings below ≈0.15 fm. On coarser lattices the complex Langevin approach breaks down. Four flavors of staggered fermions are used on Nt=4,6 and 8...
David Schaich
(Syracuse University)
7/26/16, 5:10 PM
I will present results from numerical studies of maximally supersymmetric Yang--Mills theory, focusing on the scaling dimension of the Konishi operator. Working with a lattice formulation that exactly preserves one supersymmetry at non-zero lattice spacing, we employ an improved action developed in 2015 that dramatically reduces lattice artifacts. Using this new improved action we are...
Dr
Liuming Liu
(University of Bonn)
7/26/16, 5:10 PM
We present results for the $\pi\pi$ isospin-0 scattering length calculated in twisted mass lattice
QCD. We use a set of $N_f = 2 + 1 + 1$ ensembles with pion mass
varying in the range of 230MeV - 510MeV at three different values of lattice spacing and two
$N_f=2$ ensembles with one pion mass at its physical value and one at 250MeV.
The quark disconnected diagrams are computed with...
Mr
Spraggs Matthew
(University of Southampton)
7/26/16, 5:10 PM
I present our work on the leading strange and charm quark-connected contributions to the muon anomalous magnetic moment using RBC/UKQCD physical point domain wall fermion ensembles.
Dr
Roberto Pellegrini
(The University of Edinburgh)
7/26/16, 5:30 PM
The LLR algorithm is a recent proposal for computing the density of states in lattice gauge theory. This algorithm has been tested in several bosonic models at zero and finite chemical potential with impressive results. Its original formulation is based on the simulation of the theory on restricted action intervals using local Monte Carlo updates.I will discuss a new version of the method...
Sasa Prelovsek
(University of Ljubljana)
7/26/16, 5:30 PM
The operators for simulating the scattering of two hadrons with spin will be presented. Three methods give consistent operators for PN, PV, VN and NN scattering, where P, V and N denote pseudoscalar, vector and nucleon. Explicit expressions for all irreducible representations and few lowest momenta will be shown as an example. Correct transformation properties will be demonstrated.
Dr
Tomomi Ishikawa
(RIKEN BNL Research Center)
7/26/16, 5:30 PM
In recent years, the quasi parton distribution has been introduced to extract the parton distribution functions by the lattice QCD simulation. The quasi and standard distribution share the same collinear IR singularity and the quasi distribution can be factorized into the standard distribution with perturbative matching factor. The quasi parton distribution is known to have power-law UV...
Shinji Shimasaki
(Keio University)
7/26/16, 5:30 PM
The complex Langevin method (CLM) is a promising way to perform the path integral with a complex action based on a stochastic equation for complexified dynamical variables. It is known, however, that the CLM gives wrong results in some cases, while it works, for instance, in finite density QCD in the deconfinement phase or in the heavy dense limit. In this talk, we revisit this issue starting...
Prof.
Roberto Frezzotti
(University of Rome Tor Vergata, Physics Department and INFN - Sezione di Roma Tor Vergata)
7/26/16, 5:30 PM
We show that maximally twisted mass fermions can be employed to regularize on the lattice
the fully unquenched QCD+QED theory with vanishing theta-term. We discuss how the critical
mass of the up and down quarks can be conveniently determined beyond the electroquenched
approximation by imposing that certain symmetries of continuum QCD+QED, which are broken by
Wilson terms, are restored (up...
Mr
Daniel August
(Friedrich Schiller University Jena)
7/26/16, 5:30 PM
Albeit the standard model is the most successful model of particles physics, it still has some theoretical shortcomings, for instance the hierarchy problem, the absence of dark matter, etc. . Supersymmetric extensions of the standard model could be a possible solution to these problems.
One of the building blocks of these supersymmetric models are supersymmetric gauge theories. It is...
Dr
Anosh Joseph
(University of Cambridge)
7/26/16, 5:50 PM
Maximally supersymmetric Yang-Mills theory in five dimensions has generated a lot of interest in the recent years. It takes part in the gauge-gravity duality and its finite temperature properties have been investigated recently in the planar limit. This theory is also interesting through its conjectured relationship to the six-dimensional (2,0) theory, which is still controversial. In this...
Prof.
Ying Chen
(Institute of High Energy Physics, CAS)
7/26/16, 5:50 PM
The glueball spectrum is investigated through a $N_f=2$ lattice QCD study. The gauge
configurations are generated with two degenerate flavors of quarks on anisotropic lattices. At two pion masses, say, $m_\pi=580$ MeV and $920$ MeV, we obtain the masses of the scalar, the tensor glueballs, which are in agreement with the results from the previous quenched and unquenched lattice QCD studies....
Prof.
Biagio Lucini
(Swansea University)
7/26/16, 5:50 PM
It has been shown that the recently proposed LLR method is very efficient at overcoming strong metastabilities that arise near first-order phase transition points. Here we present a systematic study of the performance of the algorithm near (pseudo)critical points on q-state Potts models for q as large as 20, in two and three dimensions. In particular, we shall focus our study on the ergodicity...
Dr
Holger Perlt
(Institute for Theoretical Physics, University of Leipzig)
7/26/16, 5:50 PM
A partially conserved axial vector current that satisfies the chiral
Ward identity is defined nonperturbatively for improved Wilson
fermions. A first application to the nucleon axial vector coupling is
presented.
Venkitesh Ayyar
(Duke University)
7/26/16, 5:50 PM
Previous studies of a simple four-fermion model with staggered fermions in 3d have shown the existence of an exotic quantum critical point, where one may be able to define a continuum limit of the Paramagnetic Strong Phase (or the PMS phase). We believe the existence of the critical point suggests a new mechanism for generating fermion masses. In this work we begin the search for this quantum...
Mr
Francesco Sanfilippo
(University of Southampton)
7/26/16, 6:10 PM
Metadynamics is a class of powerful algorithms in which the time evolution of a system is modified introducing a history-dependent potential associated with the past values of observables of choice. This has the effect of driving the system away from previously occupied states, ultimately speeding up the evolution of the system.
These methods are widely used in biochemistry and computational...
Dr
Jacques Bloch
(University of Regensburg)
7/26/16, 6:10 PM
We introduce the reweighted complex Langevin method, which enlarges the applicability range of the complex Langevin method by reweighting the complex trajectories. In this reweighting procedure both the auxiliary and target ensembles have a complex action. We validate the method by applying it to a random matrix model for QCD and to two-dimensional strong-coupling QCD, both at nonzero chemical...
Dr
pietro giudice
(University of Muenster)
7/26/16, 6:10 PM
We report on our recent results regarding numerical simulations of the four dimensional, N=1 Supersymmetric Yang-Mills theory with SU(3) gauge symmetry and light dynamical gluinos.
Mr
Ryo Sakai
(Kanazawa University)
7/26/16, 6:10 PM
We apply the higher order tensor renormalization group to two and three dimensional lattice fermion systems. To deal with the tensor network including Grassmann numbers, higher order Grassmann tensor renormalization group (HOGTRG) is introduced. Because of its deterministic property, HOGTRG is perfectly free of the sign problem. We analyze the well-known systems such as the Gross–Neveu...
Prof.
Urs Wenger
(AEC University of Bern)
7/26/16, 7:00 PM
We present a local update algorithm for gauge theories with dynamical fermions which allows simulations in fixed canonical sectors. As a first application we perform canonical simulations in N=4 supersymmetric Yang-Mills quantum mechanics without a sign problem. Compared to previous studies, we obtain results with significantly better accuracy. We also discuss some aspects of the physics of...
Mr
Hwancheol Jeong
(Seoul National University)
7/26/16, 7:00 PM
We study quark condensates using improved staggered fermions, where
zero modes of the Dirac operator give simple poles in the chiral
limit. We present a new method to identify the zero modes and
to subtract their contribution from the quark condensates.
Meanwhile we also identify the quantum numbers of
the zero modes in the staggered fermion formalism,
using the spectral flow method....
Mr
Sheng-Tai Li
(Central China Normal University)
7/26/16, 7:00 PM
We present updated studies of chiral phase transition in $N_{f}=2+1$ QCD. Simulations have been performed with Highly Improved Staggered Quarks (HISQ) on lattices with temporal extent $N_{\tau} = 6$ at vanishing baryon chemical potential. We updated our previous study (1511.00553) by extending the temperature window from (140MeV, 150MeV) to (140MeV, 170MeV). The strange quark mass was chosen...
Prof.
Pedro Bicudo
(IST - LISBOA)
7/26/16, 7:00 PM
We show the flux tubes produced by static quark-antiquark,
quark-quark and quark-gluon charges at finite temperature.
The sources are placed in the lattice with fundamental and adjoint Polyakov loops.
We compute the square densities of the chromomagnetic and chromoelectric fields above and below the phase transition.
Our results are gauge invariant and produced in pure gauge SU(3).
The...
Mr
Attilio Cucchieri
(University of São Paulo)
7/26/16, 7:00 PM
We evaluate the so-called Bose-ghost propagator in minimal Landau gauge,
for the SU(2) case in four dimensions. We consider lattice volumes up to
$120^4$ and physical lattice extents up to 13.5 fm. We investigate
discretization effects, as well as the infinite-volume and continuum
limits. A nonzero value for this quantity provides direct evidence of
BRST-symmetry breaking, related to...
Thomas Rae
(University of Wuppertal)
7/26/16, 7:00 PM
We present a study of the charmed meson and baryon ground state spectra
on the electrically neutral subset of the BMW $N_f=2+1+1$ gauge
configurations that utilise the 3-HEX smeared clover action. The
analysis focuses on a systematic evaluation of the hyperfine
mass splittings of the doubly charmed $J/\psi$ and $\eta_{c}$ mesons and
the singly charmed $D_s^*$ and $D_s$ mesons, with the...
Dr
Azusa Yamaguchi
(Software Architect)
, Prof.
Peter Boyle
(University of Edinburgh)
7/26/16, 7:00 PM
Hierarchically deflated conjugate residual
We present a new class of multigrid solver algorithm suitable for the solution of 5d chiral fermions such as Domain Wall fermions
and the Continued Fraction overlap. Unlike HDCG \cite{arXiv:1402.2585}, the algorithm
works directly on a nearest neighbour fine operator. The fine operator used is Hermitian indefinite, for example $\Gamma_5...
Mr
Matthew Kirk
(IPPP, Durham University)
7/26/16, 7:00 PM
We review the current status of HQE predictions for neutral meson mixing
and related observables. A comparison with most recent data shows a
confirmation of the HQE, but also leaves sizeable space for new physics effects.
We also point out what improved lattice inputs might be most useful for
unambiguously identifying new physics in mixing observables.
Mr
Joni Suorsa
(University of Helsinki, Helsinki Institute of Physics)
7/26/16, 7:00 PM
We study the mass anomalous dimension of SU(2) with $N_f=6$ and $N_f = 8$ in both massless and massive quark cases for a range of gauge coupling values. In the massless case we find behaviour consistent with results obtained using the Schrödinger functional method.
Mr
Benjamin Jaedon Choi
(Seoul National University / Lattice Gauge Theory Research Center)
7/26/16, 7:00 PM
We present results of matching factors for $Z_q$ and $Z_m$ calculated perturbatively at the one loop level with improved staggered quarks. We calculate $Z_q$ and $Z_m$ with HYP-smeared staggered quarks. Final results of $Z_q$ and $Z_m$ at $\mu = 2 \ \text{GeV}$ and $3 \ \text{GeV}$ in the $\overline{\text{MS}}$ scheme are given in tables.
Dr
Marina Krstic Marinkovic
(CERN)
7/26/16, 7:00 PM
The supercomputing platforms available for high performance computing based research evolve at a great rate. However, this rapid development of novel technologies requires adaptations and optimizations of the existing codes for each new machine architecture. In such context, minimizing time of efficiently porting the code on a new platform is of crucial importance. A possible solution is to...
Mr
Stefan Hofmann (Unversity of Regensburg)
(German)
7/26/16, 7:00 PM
We determine the masses and the pseudo-scalar decay constants of
charmed mesons using non-perturbatively O($a$) improved Wilson quarks.
Our analysis is based on the $N_{\rm f}=2+1$ ensembles using open
boundary conditions, generated within the CLS effort.
The status of results for 2 lattice spacings, $a\approx 0.086$ fm and
$a\approx 0.064$ fm, will be presented. The pion mass is varied...
Prof.
Tetsuya Onogi
(Osaka University)
7/26/16, 7:00 PM
The relaxation time for the fermions in the magnetic field is needed for estimate the chiral magnetic effect. However, it has been estimated only in the strong magnetic field. We discuss the relaxation time away from the strong magnetic field limit.
Prof.
Ken-ichi Ishikawa
(Hiroshima University)
7/26/16, 7:00 PM
We investigate the nature of the chiral phase transition using the RG improved gauge action and the Wilson quark action
with two degenerate quarks on $32^3\times 16$, $24^3\times 12$, and $16^3\times 8$ lattices.
We introduce RG scaling relations for both the time direction and the spacial effective masses of mesons at the chiral phase transition point.
Numerical results of effective...
Dr
Hideo Matsufuru
(High Energy Accelerator Research Organization (KEK))
7/26/16, 7:00 PM
In this work, we study SU(2) gauge theory with many flavors using
the improved domain-wall fermions, which is realized by the stout-HYP
link smearing and the optimal domain-wall formulation.
In contrast to the standard domain-wall fermions used in the previous
studies, it enables us to investigate the small fermion mass region due
to the much suppressed residual mass.
With the improved...
Prof.
Huey-Wen Lin
(Michigan State University)
7/26/16, 7:00 PM
We present a sampling of analyses concerning the gender ratio of plenary speakers during the years 2000-2016 and make comparisons with other conferences, such as the APS April meeting. Please stop by to discuss ideas for how to make our field more accessible to women and minorities. We are preparing for an in-depth survey of the lattice field and welcome any ideas or suggestions. To leave...
Prof.
Weonjong Lee
(Seoul National University)
7/26/16, 7:00 PM
We present results of the indirect CP violation parameter in the
neutral kaon system, $\varepsilon_K$ calculated using lattice QCD
inputs including $\hat{B}_K$, $\xi_0$, $V_{us}$, and $V_{cb}$.
Raza Sufian
(University of Kentucky, United States)
7/26/16, 7:00 PM
We present a lattice QCD calculation of the strange quark contribution to the proton's magnetic moment and the charge radius at the physical pion mass. The finite lattice spacing and finite volume corrections are included in a global fitting on three lattices with different lattice spacings, different volumes, and three sea quark masses. We obtain the strange magnetic moment $G^s_M(0) = -...
Prof.
Christine Davies
(University of Glasgow)
7/26/16, 7:00 PM
We report on the HPQCD calculation of the u/d HVP contribution to a_mu, discussed in arXiv:1601.03071. This allows us to obtain a total HVP contribution from u, d, s and c quarks and including an estimate of disconnected pieces and QED and isospin effects of 666(6)(12) x 10^{-10}.
Our result implies a discrepancy between the experimental determination of a_mu and the Standard Model of 3...
Mr
Felix Erben
(University Mainz)
7/26/16, 7:00 PM
Results are presented from an ongoing study of the $\rho$ resonance. We use the LapH-smearing approach in order to create correlator matrices involving $\rho$ and $\pi\pi$ interpolators. The study is done in a centre-of-mass frame and several moving frames. We are able to extract effective-energy levels by solving the GEVP of those correlator matrices. The initial exploratory study is being...
Mr
Sungwoo Park
(Seoul National University)
7/26/16, 7:00 PM
We determine hopping parameters of the Oktay-Kronfeld (OK) action for charm and bottom quarks. We use $N_f=2+1+1$ MILC HISQ ensembles (with $a\approx0.12$fm, $am_l=0.0102$, $am_s=0.0509$ and $am_c=0.635$). As a key ingredient, we compute the masses of pseudoscalar and vector mesons $B_s^{\ast}$, $D_s^{\ast}$ and their hyperfine splittings; the valence light quark is simulated with HISQ action....
Dr
Shinji Takeda
(Kanazawa University)
7/26/16, 7:00 PM
We will present an update on analysis of the phase structure for
finite temperature QCD with 3-flavor non-perturbatively O(a) improved Wilson-Clover fermions and Iwasaki gauge action.
In our previous study, it was shown that the value of kurtosis of quark condensate
at the critical point tends to deviate from that of 3D Z_2 universality class when
increasing the temporal lattice sizes...
Dr
Igor Bogolubsky
(Joint Institute for Nuclear Research)
7/26/16, 7:00 PM
We make simulations of the zero-momentum $SU(2)$ Landau gauge gluon correlator both for periodic and zero-field boundary conditions at varying $\beta$ and $L_t * L_s^3$ lattice sizes.
Ms
Ouraman Hajizadeh
(University of Graz)
7/26/16, 8:00 PM
G2-QCD, i.e. QCD with the gauge group SU(3) replaced by the exceptional
group G(2), shares many features with SU(3). But it is accessible at
finite density on the lattice, as it has no sign problem, and at the
same time has a neutron.
Therefore, this theory can sustain in princple neutron star. Using the
equation of state for this theory from lattice simulations, we solve...
Prof.
Kostas Orginos
(College of William and Mary/JLAB)
7/26/16, 8:00 PM
Results of a non-perturbative determination
of RI-MOM renormalization constants for smeared quark bi-linear operators are presented.
These operators are smeared using the gradient flow, enabling the smearing
scale to be fixed in physical units. As a result, smeared matrix elements
are free of power divergences in the lattice spacing, which allows easier
control of the continuum limit of...
Sara Tähtinen
(University of Helsinki, Helsinki Institute of Physics)
7/26/16, 8:00 PM
It is expected that SU(2) gauge theory with Nf fundamental fermions has an infrared fixed point when Nf is between ∼ 6 and 10. We study the hadron spectrum and scale setting in SU(2) gauge field theory with Nf = 2,4,6,8 using hypercubic stout smeared Wilson-clover (HEX) action. The case Nf = 2 is QCD-like, Nf = 6 is close to the lower edge of the conformal window, and Nf=8 is inside the...
Ms
Julia Kettle
(University of Edinburgh)
7/26/16, 8:00 PM
I present preliminary results for Kaon Mixing Beyond the Standard Model at the physical point.
Mr
Kevin Eckert
(WWU Muenster)
7/26/16, 8:00 PM
We report on analysis aspects within a joint ongoing effort of the
ALPHA and RQCD Collaborations to compute charmed meson masses and the
leptonic decay constants $f_{{\rm D}}$ and $f_{{\rm D}_{\rm s}}$ in
$(2+1)$-flavour lattice QCD, employing non-perturbatively O($a$) improved
Wilson quarks and the tree-level Symanzik-improved gauge action.
Our studies make use of large-volume CLS...
Mr
Sebastian Schmalzbauer
(Goethe-Universität Frankfurt, Universität Regensburg)
7/26/16, 8:00 PM
We present our results obtained from gauge cooled complex Langevin simulations in 1+1D QCD at non-zero densities in the strong coupling regime with unrooted staggered fermions. For small quark masses there are regions of the chemical potential where this method fails to reproduce correct results. In theses parameter ranges we studied the effect of different gauge cooling schemes on the...
Dr
Ion-Olimpiu Stamatescu
(I.T.P., University Heidelberg)
7/26/16, 8:00 PM
A formula expressing the fermionic determinant as an infinite
product of smaller determinants is here derived and discussed.
These smaller determinants are of a fixed size, independent of
the size of the lattice and are indexed by loops of increasing
length. The application of the formula requires convergence
considerations.
Mr
Marcin Szyniszewski
(Lancaster University)
7/26/16, 8:00 PM
The long-range t-V model of fermions on a lattice is known to exhibit a transition between a Luttinger liquid phase and a Mott insulator phase [1]. At insulating densities, one can tailor the potential energy of the model in such a way that one forces a quantum phase transition to either another insulating charge-density-wave phase, a bond-order phase or a Luttinger liquid [2]. We show how to...
Ms
Argia Rubeo
(TCD (Trinity College Dublin))
7/26/16, 8:00 PM
The gradient flow provides a new class of renormalized observables which
can be measured with high precision in lattice simulations. In principle
this allows to improve lattice actions a la Symanzik by requiring such
observables to take their continuum values already at finite lattice
spacing. At lowest order of perturbation theory we here try to identify
such improvement conditions...
Mr
Jaehoon Leem
(Seoul National University)
7/26/16, 8:00 PM
The Oktay-Kronfeld action is a highly improved version of the Fermilab action and systematically reduces heavy quark discretization effects through $\mathcal{O}(\lambda^3)$
in HQET power counting, for the heavy-light meson spectrum. To calculate $\bar{B}\rightarrow D^{(*)}\ell \bar{\nu}$ semi-leptonic form factors using Oktay-Kronfeld heavy quarks, we need to improve the heavy quark currents...
Dr
YIBO Yang
(university of Kentucky)
7/26/16, 8:00 PM
We employ dimension 4 operators to improve the local vector and axial vector currents, as the leading order approximation of the lattice conserved current, and then calculate the nucleon iso-vector axial coupling $g^3_A$ using overlap valence on Domain Wall Fermion sea. Using the equality of $g^3_A$ from $A_i$ and $A_4$ components of the axial-vector current as a normalization condition in...
Tereza Mendes
(University of São Paulo)
7/26/16, 8:00 PM
We investigate numerically the long-distance properties of gluon and
ghost propagators in Landau gauge on the lattice, for the SU(2) case. By
considering electric and magnetic gluon propagators at nonzero temperature,
we extract Debye screening masses and look for signs of deconfinement around
the critical temperature. Our results are related to the zero-temperature
behavior of...
Mr
Bernhard Lang
(University Regensburg)
7/26/16, 8:00 PM
Hadrons in lattice QCD are usually created employing smeared interpolators.
We introduce a new quark smearing that allows us to maintain small statistical errors
and good overlaps of hadronic wavefunctions with the respective ground states, also
at high spatial momenta. We test this method for various physical observables see
also arXiv:1602.05525v2 [hep-lat].
Mr
Francesco Scardino
(University of Rome "La Sapienza")
7/26/16, 8:00 PM
We introduce new extended interpolating operators made of quenched three
dimensional fermions propagating in the timeslices. Such non-local
operators are well behaved under renormalisation.
The mass of the three 3D fermions can be tuned in a controlled way to
find a better overlap of the extended operators with the states of
interest. We test these operators for baryon two-point...
Mr
Suman Baral
(Baylor University)
7/26/16, 8:00 PM
Lattice QCD calculations of quark loop operators are extremely time-consuming to evaluate. To calculate these diagrams we use stochastic noise methods, which employ a randomly generated set of noise vectors to project out physical signals. This is done with linear equation solvers like GMRES-DR (Generalized Minimum RESidual algorithm-Deflated and Restarted) for the first noise, and GMRES-Proj...
Dr
Hiroshi Ohki
(RIKEN BNL Research Center)
,
Sergey Syritsyn
(Jefferson Lab)
7/26/16, 8:00 PM
We present a progress report on the study of the CP violation effects on the nucleon from the quark chromoelectric dipole moment (cEDM) operator using $N_f=2+1$ dynamical Domain-Wall fermions. Details of the calculation and preliminary results for $m_\pi = 170$ and 250 MeV will be reported.
Dr
Takashi UMEDA
(Hiroshima Univ.)
7/26/16, 8:00 PM
We study scaling behavior of a chiral order parameter in the low density
region, performing a simulation of two-flavor lattice QCD with improved
Wilson quarks. It have been confirmed that the scaling behavior of the
chiral order parameter defined by a Ward-Takahashi identity agrees with
the scaling function of the three-dimensional O(4) spin model at zero
chemical potential. We discuss...
Mr
Eduardo Ibanez Bribian
(Instituto de Fisica Teorica UAM-CSIC)
7/26/16, 8:00 PM
We present our ongoing computation of the running of the twisted Yang-Mills coupling using gradient flow techniques. In particular, we use the gradient flow equation with twisted boundary conditions to perform a perturbative expansion of the expectation value of the Yang-Mills energy density up to fourth order at finite flow time, and regularise the respective resulting sums and integrals....
Mr
Peter Georg
(University of Regensburg)
7/26/16, 8:00 PM
On many parallel machines, the time LQCD applications spend in communication is a significant contribution to the total wall-clock time, especially in the strong-scaling limit.
We present a novel high-performance communication library that can be used as a de facto drop-in replacement in existing software.
Its lightweight nature that avoids some of the unnecessary overhead introduced by MPI...
Dr
Daniel Mohler
(Helmholtz-Institut Mainz)
7/26/16, 8:00 PM
We use a combination of quark-antiquark and $B^{(*)}K$ interpolating fields to predict the mass of two QCD bound states below the $B^*K$ threshold in the
quantum channels $J^P=0^+$ and $1^+$. The mesons correspond to the b-quark cousins of the $D_{s0}^*(2317)$ and $D_{s1}(2460)$ and have not yet been observed in experiment, even though they are expected to be found by LHCb.
In addition to...
Ms
Aya Kagimura
(Osaka University)
7/26/16, 8:00 PM
The chiral magnetic effect (CME) is the quantum anomaly related electric charge transport phenomenon along the external magnetic field, which appears in various systems possessing chiral fermions, such as the quark-gluon plasma, condensed matter physics and astrophysics.
The magnetic field dependence of the relaxation time is needed to compare the theory and experiments quantitatively....
Dr
Nikhil Karthik
(Florida International University)
7/27/16, 9:00 AM
There are plausibility arguments that QED in three dimensions has
a critical number of flavors of massless two-component fermions,
below which scale invariance is broken by the presence of bilinear
condensate. We present numerical evidences from our dynamical
lattice simulations using overlap as well as Wilson-Dirac fermions
for the absence of bilinear condensate using the following...
Stefan Schaefer
(NIC, DESY)
7/27/16, 9:00 AM
The numerical computation of many hadronic correlation functions is exceedingly difficult due to the exponentially decreasing signal-to-noise ratio with the distance between source and sink. Multilevel integration methods, using independent updates of separate regions in space-time, are known to be able to solve such problems but have so far been available only for pure gauge theory.
We...
Dr
Jon Bailey
(Seoul National University)
7/27/16, 9:00 AM
The Oktay-Kronfeld action is a highly improved version of the Fermilab action and
systematically reduces heavy quark discretization effects through $\mathcal{O}(\lambda^3)$ in HQET power counting, for the heavy-light meson spectrum. To calculate $\bar{B}\rightarrow D^{(*)}\ell \bar{\nu}$ semi-leptonic form factors using Oktay-Kronfeld heavy quarks, we need to improve the heavy quark currents...
Dr
Jochen Heitger
(University of Muenster, ITP)
7/27/16, 9:00 AM
Based on a non-perturbative matching strategy between Heavy Quark Effective Theory (HQET) at O(1/m) and finite-volume QCD, we report on our determination of the effective theory parameters of all components of the HQET heavy-light axial and vector currents in two-flavour lattice QCD. These parameters, which can be fixed by matching conditions between suitable QCD and HQET observables evaluated...
Susanne Ehret
(University of Edinburgh)
7/27/16, 9:00 AM
The Wilson flow is a promising tool to study strongly coupled theories. Its remarkable renormalisation properties allow for a meaningful formulation of the energy-momentum tensor on the lattice. The non-perturbative computation of the latter can in turn be used to study the scaling behaviour of quantum field theories. We extent recent studies on the renormalisation of the energy-momentum...
Dr
Christian Schmidt
(Universitaet Bielefeld)
7/27/16, 9:00 AM
Non-perturbative lattice QCD calculations at non-vanishing baryon
number density are hampered by the sign problem. The path
integral becomes highly oscillating and standard Monte Carlo techniques
seize working. One possible solution is the Lefschetz thimble
approach. It requires a deformation of the original integration domain
into a manifold embedded in complex space. For properly...
Mr
Judd Harrison
(Department of applied mathematics and theoretical physics, University of Cambridge)
7/27/16, 9:20 AM
We present our recent calculation of the zero-recoil form factor for the semileptonic decay $\bar{B}^0\rightarrow D^{*+} \ell^- \bar{\nu} $ using lattice QCD with 2+1+1 flavours of highly improved staggered quarks in the sea (the MILC HISQ configurations) and using non-relativistic QCD for the bottom quark. We obtain $\mathcal{F}(1)$ and combine this with the latest HFAG average of $\eta_{EW}...
Marco Cè
(Scuola Normale Superiore, Pisa, Italy & INFN, Sezione di Pisa, Italy)
7/27/16, 9:20 AM
The numerical computation of many hadronic correlation functions is exceedingly
difficult due to the exponentially decreasing signal-to-noise ratio with the
distance between source and sink. Multilevel integration methods, using independent
updates of separate regions in space-time, are known to be able to solve such
problems but have so far been available only for pure gauge theory.
We...
Dr
Paul Rakow
(University of Liverpool)
7/27/16, 9:20 AM
When QED is added to QCD simulations we have to consider the effects of massless degrees of freedom (the photons), which bring new problems which we did not have to worry about in simulations of pure QCD. Related to this, we have questions about the boundary conditions - how can we reconcile periodic boundary conditions with Gauss's Law? What is the best way of treating zero modes of the...
Dr
Yuya Tanizaki
(RIKEN BNL Research Center)
7/27/16, 9:20 AM
Path integral on Lefschetz thimbles gets much attention in the context of the sign problem, because of its usefulness in order to study the system with the complex classical action nonperturbatively. After giving its brief introduction, it is applied for studying the sign problem of the one-site Hubbard model. This model has a severe sign problem, which looks quite similar to that of the...
Dr
Stefano Piemonte
(University of Regensburg)
7/27/16, 9:20 AM
We report on our studies of the renormalization of flavor singlet quark bilinear operators in lattice QCD. The renormalization constants are determined non-perturbatively using gauge field ensembles with Nf=2 dynamical clover improved fermions. The renormalization is performed in the RI-MOM and RI-SMOM schemes. The difference between flavor singlet and non-singlet quark bilinear operators is...
Mr
Francesco Capponi
(Plymouth University)
7/27/16, 9:20 AM
We present an update about our program for the non perturbative renormalization of the energy momentum tensor. Our strategy consists in probing suitable lattice Ward identities with observables computed along the gradient flow. This set of identities exhibits many interesting qualities, arising from the UV finiteness of flowed composite operators, and can be used to measure the renormalization...
Dr
Andrew Lytle
(University of Glasgow)
7/27/16, 9:40 AM
We use both non-relativistic QCD (NRQCD) and fully relativistic formalisms to calculate
semileptonic form factors for the decays B_c -> eta_c lv and B_c -> J/psi lv over the entire q^2 range. To achieve this we employ a highly improved lattice quark action at several lattice spacings down to a=.044 fm, which allows a fully relativistic treatment of charm and simulation of the full q^2 range...
Dr
Ross Young
(University of Adelaide)
7/27/16, 9:40 AM
Using dynamical lattice simulations of the coupled theory of QED and QCD we explore some particular aspects of the periodic boundary conditions. We observe that the finite volume effects in spectroscopy are dependent upon the precise implementation of the gauge-fixing condition. We also report on the finite-volume dependence of the charge renormalisation.
Dr
Georg von Hippel
(University of Mainz)
7/27/16, 9:40 AM
We report on the determination of the renormalization factors of quark bilinears which are required among others in order to determine the nucleon scalar and tensor charges from the CLS $N_f=2$ configurations. Working in the RI'-MOM scheme, we eliminate all lattice artifacts at one-loop order using a combination of analytical results near the continuum limit and numerical calculations in...
Dr
Matthias Rottmann
(University of Wuppertal)
7/27/16, 9:40 AM
In this talk we report on the publication of the DDalphaAMG solver library. We describe its features, show examples of its application and give an overview of future developments.
Dr
Mattia Dalla Brida
(DESY - Zeuthen)
7/27/16, 9:40 AM
The perturbative calculation of gradient flow observables is technically challenging.
Current results are in fact limited to a few quantities and, in general, to low perturbative orders. Numerical stochastic perturbation theory is a potentially powerful tool that may be applied in this context. Precise results using these techniques, however, require control over both statistical and...
Dr
Chris Monahan
(Rutgers, the State University of New Jersey)
7/27/16, 10:00 AM
We present a calculation of the form factors, $f_0$ and $f_+$, for the $B_{(s)}$ to $D_{(s)}$ semileptonic decays. Our work uses the MILC $n_f=2+1$ asqtad configurations with NRQCD and HISQ valence quarks at four values of the momentum transfer $q^2$. We present preliminary results for our combined chiral-continuum extrapolation.
Mr
Simone Bacchio
(University of Cyprus - University of Wuppertal)
7/27/16, 10:00 AM
We extend the Adaptive Aggregation Based Domain Decomposition Multigrid (DD-$\alpha$AMG) algorithm to $N_f=2$ twisted mass fermions. We show numerical results for an $N_f=2$ ensemble of twisted fermions with a clover term simulated at the physical value of the pion mass. We fine-tuned the parameters to achieve a speedup comparable to the one obtained for clover fermions. We also present a...
Ms
Dorota Grabowska
(INT/UW)
7/27/16, 10:00 AM
I discuss continuing work on a recent proposal for the nonperturbative regulator for chiral gauge theories which combines domain wall fermions and gradient flow, Phys.Rev.Lett. 116 (2016) 211602. Implementing chiral gauge theories on the lattice requires not only decoupling mirror fermions to allow for fermions in complex representations, but also a road to failure for theories with fermions...
Mr
Daniel Schmidt
(Friedrich Schiller University Jena)
7/27/16, 10:00 AM
We investigate a class of quantum field theories of fermions interacting by a quartic coupling.
This includes well-known models like the Gross-Neveu model and the Thirring model.
In three spacetime dimensions, these models are used to describe properties of solid state systems like high temperature superconductors and graphene.
Additionally, they are interesting as toy models to study...
Dr
Piotr Korcyl
(University of Regensburg)
7/27/16, 10:00 AM
We determine quark mass dependent order a improvement terms of the form $b_J$ am for non-singlet scalar, pseudoscalar, vector and axialvector currents, using correlators in coordinate space. We use a set of CLS ensembles comprising non-perturbatively improved Wilson Fermions and the tree-level Luescher-Weisz gauge action at $\beta=3.4, 3.46, 3.55$ and $\beta=3.7$, corresponding to lattice...
Dr
Francesco Di Renzo
(University of Parma & INFN)
7/27/16, 10:00 AM
Monte Carlo simulations of lattice quantum field theories on Lefschetz thimbles are non trivial. We discuss a new Monte Carlo algorithm based on the idea of computing contributions to the functional integral which come from complete flow lines. The latter are the steepest ascent paths attached to critical points, i.e. the basic building blocks of thimbles. The measure to sample is thus...
Ms
Ava Khamseh
(The University of Edinburgh)
7/27/16, 10:20 AM
A new renormalization scheme is defined for fermion bilinears in QCD at non vanishing quark masses. This new scheme, denoted RI/mSMOM, preserves the benefits of the nonexceptional momenta introduced in the RI/SMOM scheme, and allows a definition of renormalized composite fields away from the chiral limit.
Dr
Hiromichi Nishimura
(RIKEN BNL Research Center)
7/27/16, 10:20 AM
We consider the spectrum of transfer matrix eigenvalues associated with Polyakov loops in lattice QCD at strong coupling. The transfer matrix at finite density is non-Hermitian, and its eigenvalues become complex as a manifestation of the sign problem. We show that the symmetry under charge and complex conjugations ensures that the eigenvalues are either real or part of a complex conjugate...
Mr
David Murphy
(Columbia University)
7/27/16, 10:20 AM
As algorithmic developments have driven down the cost of simulating degenerate light quark pairs the relative cost of simulating single quark flavors with the Rational Hybrid Monte Carlo (RHMC) algorithm has become more expensive. TWQCD has proposed an exact one-flavor algorithm (EOFA) that allows for HMC simulations of a single quark flavor without taking a square root of the fermion...
Prof.
Richard Richard Brower
(Boston University)
7/27/16, 10:20 AM
A Quantum Finite Element (QFE) Lagrangian is formulated for
a general simplicial complex approximation to a smooth Euclidean
Riemann manifold. The construction is applied to Wilson Dirac fermions
with the appropriate lattice spin connection and to phi 4th-theory
with QFE counter terms required for these theories to converge in the
continuum limit. Numerical tests are given for the...
Dr
Oliver Witzel
(University of Edinburgh)
7/27/16, 10:20 AM
First results for our calculation of semi-leptonic $B$ decays with charmed-mesons in the final state are presented. Our work is based on RBC-UKQCD's 2+1 flavor domain-wall fermion and Iwasaki gauge field configurations, We calculate the form factors by simulating the $b$ quarks using the relativistic heavy quark action, create light $u/d$ and $s$ quarks with standard domain-wall kernel, and...
Mr
Andrea Bussone
(Univeristy of Southern Denmark & CP3 Origins)
7/27/16, 10:40 AM
We present a cheap strategy to optimize Hybrid Monte Carlo parameters
in simulations of QCD and QCD-like theories. We specialize to the case of
mass-preconditioning, with multiple-time-step Omelyan integrators.
Starting from properties of the shadow Hamiltonian we show how the
optimal setup for the integrator can be chosen once the forces and
their variances are measured, assuming that...
Dr
Matthew Wingate
(University of Cambridge)
7/27/16, 10:40 AM
The width difference $\Delta \Gamma_s$ is one of three observables,
along with the mass splitting $\Delta M_s$ and the semileptonic CP
asymmetry $a^s_{\mathrm{SL}}$, whose measurements completely constrain
the physics of $B_s-\bar{B}_s$ oscillations. One of the
dominant uncertainties in theoretical calculations of the width
difference is due to not knowing matrix elements of...
Prof.
Lorenz von Smekal
(Justus-Liebig University Giessen)
7/27/16, 10:40 AM
We study the phase diagram of the fermionic Hubbard model on the hexagonal lattice in the space of on-site and nearest neighbor couplings with Hybrid-Monte-Carlo simulations. With pure on-site repulsion this allows to determine the critical coupling strength for spin-density wave formation. We compare the standard approach of introducing a small mass term, explicitly breaking the sublattice...
Asobu Suzuki
(University of Tsukuba)
7/27/16, 10:40 AM
Canonical approach is one of the powerful tools to approach the QCD phase diagram. We calculate the canonical partition function instead of the grand canonical one in the canonical approach. However, it is known that the sign problem emerges as a complex phase of the canonical partition function.
Thanks to multi-precision calculations with the canonical approach we obtained the canonical...
Dr
Andreas Athenodorou
(University of Cyprus)
7/27/16, 11:30 AM
We perform a numerical comparison of different lattice definitions of the topological charge by investigating the correlation coefficient between different definitions as well as the topological susceptibility. We use small-volume ensembles with 2 flavours of dynamical twisted mass fermions. We investigate the following definitions of the topological charge: index of the overlap Dirac...
Mr
Masaaki Tomii
(SOKENDAI)
7/27/16, 11:30 AM
We calculate the current correlators in the coordinate space and compare
them with the experimental information obtained through the spectral
functions of hadronic tau decays at ALEPH.
Lattice data are obtained with 2+1 Mobius domain-wall fermions at
three lattice spacings 0.044, 0.055 and 0.080 fm and the continuum limit
is taken.
On the experimental side, there is no information for...
Prof.
Kazuyuki Kanaya
(CiRfSE, Univ. Tsukuba)
7/27/16, 11:30 AM
The energy-momentum tensor and the equation of state are studied in finite-temperature (2+1)-flavor QCD with improved Wilson quarks, using the gradient flow method proposed by Makino and Suzuki. Although the up and down quarks are heavy yet ($m_{\rm PS}/m_V \approx 0.63$), we obtain reasonable results, suggesting that the method works well. We also report on the results on the chiral...
Dr
Meifeng Lin
(Brookhaven National Laboratory)
7/27/16, 11:30 AM
We present updated strategies and results of combining hand-tuning with the R-Stream source-to-source auto-parallelizing compiler to transform the serial implementation of the domain wall fermion Dslash kernel in CPS into an efficient parallel code targeting the Intel Xeon CPUs. The R-Stream compiler performs preliminary optimizations of the input Dslash code, including a novel iteration space...
Prof.
Margarita Garcia-Perez
(Instituto de Fisica Teorica UAM-CSIC)
7/27/16, 11:30 AM
We derive the perturbative expansion of Wilson loops to order g^4 in a SU(N) lattice gauge theory with twisted boundary conditions. Our expressions show that the thermodynamic limit is attained at infinite N for any number of lattice sites and allow to quantify the deviations from volume independence at finite large N as a function of the twist. The effect of adjoint Wilson fermions will be...
Eduardo Royo
(Universidad de Zaragoza)
7/27/16, 11:50 AM
Understanding the role of the $\theta$ parameter in QCD and its
connection with the strong CP problem and axion physics is one of the
major challenges for high energy theorists. Due to the sign problem,
at present only the QCD topological susceptibility is well
known. Using an algorithmic approach that could potentially be
extended to QCD, we study as a first step the $\theta$-dependence...
Mr
Arjun Gambhir
(College of William and Mary/JLab)
7/27/16, 11:50 AM
Computing disconnected diagrams on the lattice involves taking the trace of the inverse of the Dirac operator. This is a computationally challenging problem, however recent algorithmic improvements such as low mode averaging and hierarchical probing have increased the efficiency of this trace estimation. We detail an algorithm that builds upon hierarchical probing by deflating the near null...
Randy Lewis
(York University)
7/27/16, 11:50 AM
SU(2) gauge theory with a single fermion in the fundamental representation is a minimal non-Abelian candidate for the dark sector. Having only a single flavor provides a natural mechanism for stabilizing dark matter on cosmological timescales. Preliminary lattice results will be presented and discussed in the context of dark matter phenomenology.
Dr
Nazario Tantalo
(Rome University Tor Vergata and INFN sez. of Rome Tor Vergata)
7/27/16, 11:50 AM
In Ref.[1] we proposed a method for calculating leptonic (and semileptonic) decay rates of pseudoscalar mesons including $O(\alpha)$ electromagnetic corrections. Because of the presence of infrared divergences, this requires the calculation of contributions with both virtual and real photons. We have shown that the real photon contribution, by integrating up to photon momenta of the order of...
Prof.
Masanori Okawa
(Hiroshima University)
7/27/16, 11:50 AM
Meson masses and decay constants in the large N limit of SU(N) gauge theory is estimated from the twisted space-time reduced model. To this end, we introduce a new smearing method which enables us to obtain reliable values for these quantities.
Ms
Jana Günther
(University of Wuppertal)
7/27/16, 11:50 AM
An efficient way to study the QCD phase diagram at small finite density is to extrapolate thermodynamical observables from imaginary chemical potential. In this talk we present results on several observables for the equation of state to order (muB/T)^6. The observables are calculated along the isentropic trajectories in the (T, muB ) plane corresponding to the RHIC Beam Energy Scan collision...
Prof.
Antonio Gonzalez-Arroyo
(Instituto de Fisica Teorica UAM/CSIC)
7/27/16, 12:10 PM
We use a recently formulated expression for computing meson masses at
large N to study the spectrum of two-dimensional QCD in the large N
limit. The model serves as a testing ground to explore methodology
of meson mass determination with different techniques and versions
of lattice fermions.
Mr
Matthias Puhr
(University of Regensburg)
7/27/16, 12:10 PM
We present a method for the numerical calculation of derivatives of
functions of general complex matrices which also works for implicit
matrix function approximations such as Krylov-Ritz type algorithms. An
important use case for the method is the overlap Dirac operator at
finite quark chemical potential. The evaluation of the overlap Dirac
operator at finite chemical potential calls for...
Dr
Silvano Simula
(INFN - Roma Tre)
7/27/16, 12:10 PM
Electromagnetic effects on the leptonic decay rates pi+ -> mu+ nu and K+ -> mu+ nu are evaluated for the first time on the lattice.
Following a method recently proposed in Ref. [1] the emission of virtual photons at leading order in the e.m. coupling is evaluated on the lattice with the subtraction of the infrared divergence computed for a point-like meson at finite lattice volume.
The...
Dr
Falk Bruckmann
(University of Regensburg)
7/27/16, 12:10 PM
We simulated the asymptotically free two-dimensional O(3) model at nonzero chemical potential through dual variables free of the sign problem. The system undergoes a quantum phase transition when mu reaches the particle mass (generated dynamically similar to QCD). The density follows a square root universal for repulsive bosons in one spatial dimension. We have also measured the spin...
Mr
Senia Valgushev
(Regensburg University)
7/27/16, 12:10 PM
One of the macroscopic manifestations of the Chiral anomaly in a matter with Dirac fermions is a large negative magnetoresistivity in strong magnetic fields, which is common feature of Weyl- and Dirac semimetals and QCD. However, most of previous studies have been done in the linear response approach in non-interacting theory. We study Magnetoresistivity in a model of Dirac semimetal using...
Monika Blanke
(Karlsruhe Institute of Technology)
7/28/16, 9:00 AM
In this talk I review the implications of recent lattice QCD results on the phenomenology of flavour and CP-violating meson decays. Precise lattice QCD results for hadronic matrix elements, decay constants and form factors play a crucial role in the determination of CKM matrix elements and in the identification of possible new physics contributions to flavour violating observables. I also...
ran zhou
(Fermi National Accelerator Laboratory)
7/28/16, 9:45 AM
Heavy meson decays are used to extract the fundamental parameters
in Standard Model such as CKM matrix elements and probe new physics
beyond the Standard Model. Lattice QCD provides a non-perturbative
method to calculate the matrix elements in these processes. In this talk, I
will review recent progress in the study of B and D meson
decay constants, semileptonic decay form factors, B and...
Dr
Amy Nicholson
(UC Berkeley)
7/28/16, 10:15 AM
While the discovery of non-zero neutrino masses is one of the most important accomplishments by physicists in the past century, it is still unknown how and in what form these masses arise. Lepton number-violating neutrinoless double beta decay is a natural consequence of Majorana neutrinos and many BSM theories, and several experimental efforts are involved in the search for these processes....
Agostino Patella
(CERN and Plymouth U.)
7/28/16, 11:15 AM
When aiming at a percent precision in hadronic quantities calculated by means of lattice simulations, isospin breaking effects become relevant. These are of two kinds: up/down mass splitting and electromagnetic corrections. In order to properly account for the latter, a consistent formulation of electrically-charged states in finite volume is needed. In fact on a periodic torus Gauss' law and...
38.
Charge radii and higher electromagnetic moments with lattice QCD in nonuniform background fields
Dr
Zohreh Davoudi
(MIT)
7/28/16, 2:00 PM
Nonuniform background electromagnetic fields, once implemented in lattice QCD calculations of hadronic systems, provide a means to constrain a large class of electromagnetic properties, from higher electromagnetic moments and charge radii to electromagnetic form factors. In this talk, I present the recent theoretical developments in realizing general background fields in periodic hypercubic...
Yusuke Namekawa
(University of Tsukuba)
7/28/16, 2:00 PM
We present our results of charm physics in
$N_f=2+1$ lattice QCD. Our calculation is
performed on configurations generated
with Iwasaki gauge and the six stout smeared
$O(a)$-improved Wilson quark actions on a $96^4$ lattice
at $\beta=1.82$ ($a^{-1} = 2.3$ GeV) with the spatial
extent $L=8.1$ fm. The pion mass is almost physical
$m_\pi=145$~MeV. The relativistic heavy quark action
is...
Prof.
Johan Bijnens
(Lund University)
7/28/16, 2:00 PM
Recent progress in mesonic Chiral Perturbation Theory at finite volume
and/or with twisted boundary conditions will be discussed. Topics include
the finite volume at two-loop order calculations of masses and decay constants
for the pseudoscalar of the normal case for two and three flavours [1],
partially quenched three flavour [2] and the case for different patterns of
spontaneous...
Dr
Jon-Ivar Skullerud
(Maynooth University)
7/28/16, 2:00 PM
We present results for correlators and spectral functions of open charm mesons using 2+1 flavours of clover fermions on anisotropic lattices. The D mesons are found to melt close to the deconfinement crossover temperature $T_c$. Our preliminary results suggest a shift in the thermal D meson mass below $T_c$.
Prof.
Luigi Del Debbio
(Edinburgh)
7/28/16, 2:00 PM
We study the phenomenology of a specific model of strongly interacting dynamics beyond the Standard Model, and derive the current bounds on the low-energy constants that describe the large-distance behaviour of the model.
We deduce from these bounds the required accuracy for lattice simulations to have an impact on searches for new physics beyond the Standard Model.
Dr
Laurent Lellouch
(CNRS & Aix-Marseille U.)
7/28/16, 2:20 PM
For the Budapest-Marseille-Wuppertal collaboration
We present a lattice study of the u, d and s quark contents of the nucleon, determined using the Feynman-Hellmann theorem. Results are obtained from twenty-nine high-statistics simulations with four flavors of O(a)-improved Wilson quarks, four lattice spacings and a variety of quark masses.
Mr
Atsuro Ikeda
(Osaka University)
7/28/16, 2:20 PM
We study the charm quark diffusion coefficient from nonzero momentum correlator in temporal channel on the quenched lattice. Euclidean correlator in temporal channel with zero momentum is constant as a function of the imaginary time because of the charge conservation. However this quantity with finite momentum is dependent on imaginary time and is more sensitive to the low energy structure of...
Mr
Marco Garofalo
(University of Edinburgh)
7/28/16, 2:20 PM
We consider a field theoretical model where a SU(2) doublet fermion, subjected to non-abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an irrelevant Wilson-like term. Despite the presence of these two chiral breaking operators in the Lagrangian, an exact symmetry acting on fermions and scalars prevents perturbative mass corrections. In the phase...
Dr
Elvira Gamiz
(University of Granada)
7/28/16, 2:20 PM
We present an update of our calculation of the $K_{\ell 3}$ form factor $f_+^{K \pi}(0)$, with added statistics and the inclusion of new ensembles with smaller lattice spacing. In addition, we now also include a study of finite volume effects using a version of staggered ChPT that includes the effects of twisted boundary conditions.We also examine the implications for the unitarity of the CKM...
Mr
David Tims
(Trinity College Dublin)
7/28/16, 2:20 PM
Charmed meson spectroscopy with data generated by the Hadron Spectrum
Collaboration is presented, using two ensembles with different light
sea-quark masses to investigate the effect of the sea quark mass on the
spectrum. Initial results from an investigation of the contribution of
the disconnected quark-line diagram on the charmonium hyperfine
splitting will be presented, including a...
Dr
Chia Cheng Chang
(LBNL)
7/28/16, 2:40 PM
Momentum-space derivatives of matrix elements can be related to their coordinate-space moments through the Fourier transform. We derive these expressions as a function of momentum transfer $Q^2$ for asymptotic in/out states consisting of a single hadron. We calculate corrections to the finite volume moments by studying the spatial dependence of the lattice correlation functions. This method...
Dr
Tomasz Korzec
(Bergische Universität Wuppertal)
7/28/16, 2:40 PM
We investigate the influence of dynamical charm quarks on various observables. For observables without explicit charm-quark dependence, decoupling applies and the effects are expected to be small. However, we also study quantities with explicit charm-quark dependence, like the charmonium mass spectrum, where decoupling does not apply.
Our study puts an emphasis on careful continuum...
Dr
Enno E. Scholz
(University of Regensburg)
7/28/16, 2:40 PM
The leptonic decay-constant ratio $f_K/f_\pi$ is calculated from lattice-QCD simulations using $N_f=2+1$ dynamical fermion flavors in the clover-improved formulation and 2-HEX smearing. The simulations were performed at a range of mass-degenerate light quarks including the physical point and at various lattice couplings and volumes, allowing to quantify all relevant sources of systematic...
Mr
Maurizio Alberti
(University of Wuppertal)
7/28/16, 2:40 PM
We report on the progress in the study of a five-dimensional SU(2) Gauge-Higgs Unification model.
In the non-perturbative study, the Higgs mechanism is triggered by the spontaneous breaking of a
global symmetry. In the same region of the phase diagram, we observe both dimensional reduction
and the ratio of Higgs and Z boson masses to take the value known from experiment.
We present the...
Dr
Graham Moir
(University of Cambridge)
7/28/16, 3:00 PM
We present an extensive study of isospin $1/2$ coupled-channel $D\pi$, $D\eta$ and $D_{s}\bar{K}$ scattering,
as well as isospin $3/2$ elastic $D\pi$ scattering, from $N_{f} = 2+1$ lattice QCD. Our use of distillation in combination with variationally optimised interpolating operators allows us to extract statistically precise two-meson spectra, which we use to constrain scattering amplitudes...
Dr
Yong-Chull Jang
(Los Alamos National Laboratory)
7/28/16, 3:00 PM
We present the status of the calculation of the nucleon iso-vector axial and vector form factor using the MILC $N_f=2+1+1$ HISQ ensembles with lattice spacings $a=0.12, 0.09$, and $0.06\;\mathrm{fm}$ and three values of light quark masses corresponding to pion masses $310, 220, 130\;\mathrm{MeV}$. Valence quarks are simulated with the clover action. A number of techniques to increase the...
Prof.
Axel Maas
(University of Graz)
7/28/16, 3:00 PM
The spectacular success of perturbation theory in electroweak physics hinges on the validity of the Froehlich-Morchio-Strocchi mechanism. This mechanism allows the determination of the spectrum of physical, gauge-invariant states using perturbation theory if a Brout-Englert-Higgs effect is present. For this mechanism to work two preconditions have to be met. One is the structural requirement...
Dr
Evan Weinberg
(Boston University)
7/28/16, 3:00 PM
As the push towards the exascale enables increasingly accurate lattice calculations, the inversion of the Dirac matrix becomes a superlinearly growing expense. Adaptive algebraic multigrid (AAMG) methods for all fermion discretizations are essential to address this phenomena of critical slowing down. As a preconditioner, AAMG expedites Dirac matrix inversions with manageable start up costs....
Dr
Hiroshi Ohno
(University of Tsukuba)
7/28/16, 3:00 PM
We study charmonium spectral functions at finite temperature by using stochastic reconstruction methods. Our quenched lattice QCD simulations are performed with the standard plaquette gauge and the $O(a)$-improved Wilson fermion actions on 192$^3 \times N_\tau$ lattices with $N_\tau$ = 96--32, which corresponds to temperatures from 0.73$T_c$ to 2.2$T_c$. To reconstruct the charmonium spectral...
Dr
Roger Horsley
(University of Edinburgh)
7/28/16, 3:00 PM
The SU(3) flavour symmetry breaking expansion in up, down and
strange quark masses is extended from hadron masses to meson
decay constants. This allows a determination of the ratio of
kaon to pion decay constants in QCD. Furthermore when using
partially quenched valence quarks the expansion is such that
SU(2) isospin breaking effects can also be determined. It is
found that the lowest...
Dr
Alexander Rothkopf
(Institute for Theoretical Physics, Heidelberg University)
7/28/16, 3:20 PM
The concept of a screening mass is a powerful tool to simplify the intricate physics of in-medium test charges surrounded by light charge carriers. While it has been successfully used to describe electromagnetic properties, its definition and computation in QCD is plagued by questions of gauge invariance and the presence of non-perturbative contributions from the magnetic sector.
Here we...
Dr
Ken-Ichi Ishikawa
(Hiroshima University)
7/28/16, 3:20 PM
The most computationally demanding part of Lattice QCD simulations is
solving quark propagators.
Quark propagators are typically obtained with a linear equation solver utilizing HPC machines.
The success of Lattice QCD simulations owes much to the development of numerical algorithms and
optimization for the quark solver, and evolution of HPC machines.
The CCS QCD Benchmark is a benchmark...
Dr
Christopher Thomas
(University of Cambridge)
7/28/16, 3:20 PM
I will discuss a recent lattice QCD investigation of $D$ $K$ scattering relevant for near-threshold charm-strange mesons such as the enigmatic $D_s(2317)$. By employing a range of techniques we extracted precise finite-volume spectra in a number of different channels. These were used to map out the energy dependence of the scattering phase shift and from the singularity structure of the...
Nesreen Hasan
(Bergische Universitaet Wuppertal)
7/28/16, 3:20 PM
We describe a lattice approach for directly computing momentum derivatives
of nucleon matrix elements using the Rome method, which we apply
to obtain the isovector magnetic moment and Dirac radius. We present preliminary
results calculated at the physical pion mass using a 2HEX-smeared
Wilson-clover action from the Budapest-Marseille-Wuppertal collaboration.
For removing the effects of...
Mr
Pascal Toerek
(University of Graz)
7/28/16, 3:20 PM
The description of electroweak physics using perturbation theory is highly successful. Though not obvious, this is due to a subtle field-theoretical effect, the Fröhlich-Morchio-Strocchi mechanism, which links the physical spectrum to that of the elementary particles. This works because of the special structure of the standard model, and it is not a priori clear whether it works for...
Kim Maltman
(York University)
7/28/16, 3:20 PM
We discuss the current status of the determination of V_us based on
flavor-breaking finite energy sum rule analyses of non-strange and
strange hadronic tau decay data, highlighting the role of lattice
input in providing a means of investigating the reliability of the
OPE representation for the relevant flavor-breaking polarization
combination employed in this analysis, and in quantifying...
Dr
Jeremy Green
(Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
7/28/16, 3:40 PM
A lattice QCD calculation of the light and strange axial form factors $G_A$ and $G_P$ of the nucleon will be reported. Disconnected diagrams were calculated using hierarchical probing, and a clear nonzero signal was obtained. We pay special attention to renormalization, which we determined nonperturbatively, including the mixing between light and strange quarks. This calculation was done on a...
Dr
Ruizi Li
(Indiana University)
7/28/16, 3:40 PM
We review our work done to optimize the staggered conjugate gradient(CG) algorithm in the MILC code for use with the Intel Knights Landing (KNL) architecture. KNL is the second generation Intel Xeon Phi processor. It is capable of massive thread parallelism, data parallelism and high on-board memory bandwidth, and is being adopted in supercomputing centers for scientific research. The CG...
Mr
Antonio Cox
(University of Regensburg)
7/28/16, 3:40 PM
Early theoretical studies and lattice simulations predicted the charmed-strange mesons $D_{s0}^{*}(2317)$ and $D_{s1}(2460)$ to be broad states lying above the thresholds, $DK$ and $D^{*}K$, respectively. Experiments found narrow states below threshold. We present results of a high statistics $Nf=2$ study with a lattice spacing of approximately $0.071$ fm, taking explicitly into account the...
Mr
Aman Steinberg
(Uni Mainz)
7/28/16, 3:40 PM
Thermal screening masses associated to the conserved vector current are calculated both in a weak-coupling and a lattice QCD approach. The inverse of a screening mass can be understood as the length scale over which an external electric field is screened in a QCD medium. The comparison of screening masses in the zero and non-zero Matsubara frequency sectors shows good agreement of the...
Dr
Hiroshi Ohki
(RIKEN BNL Research Center)
7/28/16, 3:40 PM
We present a novel approach to determining Vus which employs inclusive
strange hadronic tau decay data and hadronic vacuum polarization functions
(HVPs) computed on the lattice. The experimental and lattice data are
related through dispersion relations which employ a class of weight functions
which are products of factors having poles at Euclidean Q^2.
Implementing this approach using...
Dr
Takumi Iritani
(Stony Brook University)
7/28/16, 4:30 PM
In lattice QCD, both direct method for eigen-energy extraction and HAL QCD method for potential are employed so far to study hadron interactions. The scattering phase shifts, for example, are obtained through the Luscher’s finite volume formula for the former,
but they are calculated via the Schroedinger equation with the potential in the infinite volume for the latter.
Although both...
Prof.
Yoshinobu Kuramashi
(University of Tsukuba/RIKEN AICS)
7/28/16, 4:30 PM
We present preliminary results for nucleon form factors including the axial charge and the Dirac radius in 2+1 flavor QCD at the almost physical pion mass on a $96^4$ lattice with the lattice spacing of 0.084 fm. The configurations are generated with the stout-smeared $O(a)$-improved Wilson quark action and the Iwasaki gauge action at beta=1.82. A large spatial volume of (8.1fm$)^3$ allows us...
Dr
Gergely Endrodi
(University of Frankfurt)
7/28/16, 4:30 PM
We study the QCD phase diagram at nonzero isospin chemical potential
using 2+1 flavors of staggered fermions with physical quark masses at
different lattice spacings and volumes. The talk focuses on the
transition to the pion condensation phase at high chemical potentials.
This phase is characterized by a proliferation of low modes that slow
down the simulation considerably and...
Dr
Tadeusz Janowski
(CP3-Origins)
7/28/16, 4:30 PM
SU(2) gauge theories with two quark flavours in the fundamental
representation are among the most promising theories of composite dynamics
describing the electroweak sector. Three out of five Goldstone bosons in
these models become the longitudinal components of the W and Z bosons giving
them mass. Like in QCD we expect a spectrum of excitations which appear as
resonances in vector boson...
Dr
Mattia Bruno
(Brookhaven Natl. Lab.)
7/28/16, 4:30 PM
Perturbation theory plays a significant role in some lattice calculations, in particular in those related to weak processes. Here we discuss the possibility to calculate the Wilson Coefficients of the leading order electro-weak effective Hamiltonian of the Standard model to all order in the strong coupling constant, using lattice simulations.
Mr
Viljami Leino
(University of Helsinki)
7/28/16, 4:50 PM
We present preliminary results of the gradient flow running coupling in SU(2) gauge theory with 6 massless fundamental representation fermion flavours. We use the Schrödinger functional boundary conditions, which allows us to also measure the mass anomalous dimension. Our results, using the HEX-smeared Wilson-clover action, are consistent with perturbative running on the weak coupling region...
Prof.
Sinya Aoki
(Yukawa Institute for Theoretical Physics, Kyoto University)
7/28/16, 4:50 PM
Since the energy shift of two-baryon system due to the finite volume is negative for the attractive interaction, the Lueshcer's finite volume formula gives the phase shift at negative squared momentum, $k^2 < 0$, for the ground state. The phase shift at $k^2<0$ is not physical in the infinite volume where $k^2$ are all positive except for bound states, but it corresponds to the analytic...
Dr
Tim Harris
(Helmholtz-Institut Mainz)
7/28/16, 4:50 PM
We present updated results on the isovector electromagnetic form factors and axial coupling of the nucleon calculated using the CLS ensembles with $N_{\mathrm f}=2+1$ flavours of Wilson fermions. Systematic effects are investigated by covering a range of lattice spacings and pseudoscalar masses. Efficient variance reduction is achieved with the truncated solver method. The strategy to...
Dr
Christopher Kelly
(Columbia University)
7/28/16, 4:50 PM
We discuss recent progress by the RBC & UKQCD collaborations in the lattice calculation of the measure of Standard Model direct CP violation, \epsilon', with physical kinematics. We present results with improved systematic errors resulting from the use of step-scaling to
reduce the renormalization error, an analysis that also takes into account the one-loop-suppressed mixing with the G_1...
Dr
Bastian Brandt
(University of Frankfurt)
7/28/16, 4:50 PM
We investigate the phase diagram of QCD at finite isospin chemical potential using 2+1 flavours of staggered fermions with physical quark masses at different lattice spacings and volumes. In this talk we focus on the region of small isospin chemical potential below the phase boundary to the pion condensation phase and investigate the change of the transition temperature with the chemical...
Dr
Giannis Koutsou
(The Cyprus Institute)
7/28/16, 5:10 PM
The nucleon electromagentic and axial form factors are presented using an N$_\textrm{f}$=2 twisted mass fermion ensemble with pion mass of 135 MeV. Dipole masses for the momentum dependence of the form factors are extracted and compared to experiment, as is the nucleon magnetic moment and charge and magnetic radii.
Prof.
Norman Christ
(Columbia University)
7/28/16, 5:10 PM
The rare kaon decays K+ -> pi+ nu nu-bar are highly suppressed in the standard model and thus provide an ideal place to search for new physics beyond the standard model. These decays are the principal objective of a new experiment, NA62 at CERN. Another new experiment to search for KL -> pi0 nu nu-bar is now underway at J-PARC. Given the goal of 10% precision by NA62, it is important to...
Prof.
Benjamin Svetitsky
(Tel Aviv University)
7/28/16, 5:10 PM
The SU(4) gauge theory with two flavors of Dirac fermions in the sextet representation shares features of a candidate for a composite Higgs model. The analogue of the Higgs multiplet of the Standard Model lives in the Goldstone manifold resulting from spontaneous breaking of the global symmetry SU(4) to SO(4). The Higgs potential arises from interaction with the particles of the Standard...
Mr
Aleksandr Nikolaev
(ITEP)
7/28/16, 5:10 PM
In this talk we present our results on the low-temperature scan of the phase diagram of dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark...
Takeshi Yamazaki
(Univ. of Tsukuba)
7/28/16, 5:10 PM
Recently it was raised a possibility that calculation of the nucleus correlation functions suffers from a significant systematic error due to excited state contributions depending on the choice of the source operator.
In order to investigate the operator dependence of the nucleus correlation functions,
we have performed a high precision calculation employing the exponential smeared and...
Dr
Alejandro Vaquero
(INFN Sezione Milano Bicocca)
7/28/16, 5:30 PM
The latest results from the Twisted-Mass collaboration on disconnected diagrams at the physical value of the pion mass are presented. In particular, we focus on the sigma terms, the axial charges and the momentum fraction. A detailed error analysis for each observable follows, showing the strengths and weaknesses of the one-end trick. Alternatives are discussed.
Mr
Takuya Sugiura
(RCNP, Osaka University)
7/28/16, 5:30 PM
HAL QCD collaboration has mostly considered the lowest order potential
of the derivative expansion so far based on the assumption that higher
order terms yield minor correction in low energy region.
In this study, we aim at investigating the properties of HAL QCD's non-local
potentials when the derivative expansion is explicitly performed to higher order.
We report the result of our model...
168.
Towards Partial Compositeness on the Lattice: Baryons with Fermions in Multiple Representations
Mr
William Jay
(University of Colorado Boulder)
7/28/16, 5:30 PM
We describe our recent lattice study of SU(4) gauge theory with dynamical
Wilson-clover fermions in the fundamental and sextet representations. In
this theory, a unique type of baryon consists of quarks in both
representations. The spectrum of these "chimera baryons" turns out to have
enlightening interpretations in terms of large-N expansion and the
non-relativistic quark model. We also...
Mr
Lukas Holicki
(Justus-Liebig-University Giessen)
7/28/16, 5:30 PM
Lattice simulations of two-colour QCD can be performed at finite density without sign problem and by now have a long history already. The physics of the bosonic diquark baryons is believed to be fairly well understood and qualitatively resembles QCD at finite isospin density with pion condensation. There is good guidance from effective field theory predictions and model studies of the BEC-BCS...
Dr
Jarno Rantaharju
(CP3-Origins)
7/28/16, 5:50 PM
Four fermion interactions appear in many models of Beyond Standard Model physics. In composite Higgs models Standard Model fermion masses can be generated by four fermion terms. They are also expected to modify the dynamics of the new strongly interacting sector. In particular in technicolour models it has been suggested that they can be used to break infrared conformality and produce a...
Mr
Bardiya Bahrampour
(Justus-Liebig University Giessen)
7/28/16, 5:50 PM
The strong coupling expansion of the lattice gauge action leads to a Polyakov loop model that effectively describes the gluodynamic at low temperatures and together with the hopping expansion of
the fermion determinant allows for insights into the QCD phase diagram at finite density and low temperatures, although the accessible pion masses are rather large.
At high temperatures the strong...
Dr
Rajan Gupta
(Los Alamos National Laboratory)
7/28/16, 5:50 PM
High precision estimates of the iso-vector nucleon charges g_A, g_S and g_T, electric, magnetic and axial form factors measured on four ensembles of 2+1 flavor clover fermions will be presented and compared with those from clover-on-HISQ calculations. An analysis of systematic uncertainties due the lattice volume, lattice spacing, quark mass and renormalization will also be presented for both...
Mr
Andrew Lawson
(University of Southampton)
7/28/16, 5:50 PM
The rare decays of a kaon into a pion and a lepton/antilepton pair proceed via a flavour changing neutral current and therefore first arise in the Standard Model only as a second order electroweak interaction. This natural suppression makes these decays sensitive to the effects of potential New Physics. However the rare decay channels K+ -> pi+ l+ l- are dominated by contributions from...
Mr
Takaya for HAL QCD Collaboration Miyamoto
(Yukawa Institute for Theoretical Physics, Kyoto University)
7/28/16, 5:50 PM
We investigate the 2-baryon system with the isospin 1/2
including one charm quark, namely, $\Lambda_c N$ and $\Sigma_c N$.
Although this system is similar to the $\Lambda N$ and $\Sigma N$ system,
the interaction of this charmed 2-baryon system above $\Sigma_c N$ threshold
might be quite different from its hyperon counter part, due to the smaller mass splitting
between $\Sigma_c$ and...
Daisuke KAWAI
(Kyoto University)
7/28/16, 6:10 PM
The first principle calculation of hadron-hadron interaction is an important step toward the understanding of nuclear physics from QCD. The HAL QCD method is largely contributing to this purpose by making it possible to calculate nuclear potentials in lattice QCD. We now try to extend the HAL QCD method to systems such as $\pi-\pi$ and $\pi-N$, where pair creation and annihilation of quarks...
Dr
Jeffrey Greensite
(San Francisco State University)
7/28/16, 6:10 PM
The relative weights method is applied to extract the effective Polyakov line action corresponding to SU(3) gauge theory with dynamical staggered fermions, and this theory is solved, at finite chemical potential and a few sample temperatures, quark masses, and couplings, by a mean field technique. The effective Polyakov line action is highly non-local, and in at least one case we encounter...
Mr
Martin Hansen
(CP3-Origins, University of Southern Denmark)
7/28/16, 6:10 PM
We present new results from our ongoing study of the SU(3) "sextet model" with two flavors in the 2-index symmetric representation of the gauge group. The simulations use unimproved Wilson fermions and to address the issue of whether or not the model is inside the conformal window, we measure the meson and baryon spectrum. To better understand the overall behavior of the lattice model we map...
Aaron Meyer
(University of Chicago/Fermilab)
7/28/16, 6:10 PM
The nucleon axial form factor is a dominant contribution to errors in neutrino oscillation studies. Lattice calculations have the potential to make an impact on controlling theory errors by disentangling the effects of nuclear corrections and nucleon form factors. In this talk, I will present preliminary results on a blinded calculation of $g_A$ and the axial form factor using HISQ staggered...
Prof.
Heng-Tong Ding
(Central China Normal University)
7/29/16, 9:00 AM
I will review some recent selected results from Lattice QCD computations at nonzero temperature and density.
Prof.
Seyong Kim
(Sejong University)
7/29/16, 9:45 AM
Heavy quark system offers opportunities and challenges for theoretical (and experimental) investigations on the properties of Quark-Gluon Plasma (QGP). Here, recent progresses in the studies of heavy quarks and quarkonia in QGP are discussed. In particular, the results from the calculation of heavy quark kinetic/chemical equilibration in QGP and those from the studies of quarkonia behaviors at...
Prof.
Kurt Langfeld
(Plymouth University)
7/29/16, 10:15 AM
Although Monte Carlo calculations using Importance Sampling have matured into the most widely employed method for determining first principle results in QCD, they spectacularly fail for theories with a sign problem or for which certain rare configurations play an important role. Non-Markovian Random walks, based upon iterative refinements of the density-of-states, overcome such overlap...
Prof.
Aleksi Kurkela
(CERN and Univ. Stavanger)
7/29/16, 11:15 AM
Phenomenology of Heavy Ions and LQCD
Prof.
Hiroshi Suzuki
(Kyushu University)
7/29/16, 12:00 PM
It is conceivable that the construction of the energy-momentum tensor in lattice field theory enlarges our ability in lattice field theory and also deepens our understanding on the energy-momentum tensor in the non-pertubative level. In this talk, I will review recent developments in this enterprise.
Mr
Tobias Rindlisbacher
(ETH Zürich)
7/29/16, 2:00 PM
The CP(N-1) model in 2D is an interesting toy model for 4D QCD as it possesses confinement, asymptotic freedom and a non-trivial vacuum structure. Due to the lower dimensionality and the absence of fermions, the computational cost for simulating 2D CP(N-1) on the lattice is much lower than the one for simulating 4D QCD. However to our knowledge, no efficient algorithm for simulating the...
Prof.
Guido Martinelli
(Universita' di Roma "La Sapienza" and Cern)
7/29/16, 2:00 PM
We investigate the topological properties of $N_f = 2 + 1$ QCD with
physical quark masses, both at zero and finite temperature. At zero
temperature both finite size and finite cut-off effects have been
studied by comparing the continuum extrapolated results for the
topological susceptibility $\chi$ with the predictions from chiral
perturbation theory. At finite temperature, we explore...
Mr
Justus Tobias Tsang
(University of Southampton)
7/29/16, 2:00 PM
This talk will provide an overview of RBC/UKQCD's charm project on their 2+1 flavour physical point ensembles using Domain Wall Fermions for the light as well as for the charm quarks. I will discuss the analysis strategy and present the latest results for the $D$ and $D_s$ decay constants. I will also outline the wider charm-related physics program of RBC/UKQCD.
Dr
Benoît Blossier
(CNRS/LPT Orsay)
7/29/16, 2:00 PM
In many lattice simulations with dynamical quarks, radial or orbital
excitations of hadrons lie near multihadron thresholds: it makes the
extraction of excited states properties more challenging and cqn introduce
some systematics difficult to estimate without an explicit computation of
correlators using interpolating fields strongly coupled to multihadronic
states. In a recent study...
Dr
Claudio Bonati
(Università di Pisa)
7/29/16, 2:00 PM
Studies of the large N behaviour of the topological properties of gauge theories typically focused on the large N scaling of the topological susceptibility. A much more difficult task is the study of the behaviour of higher cumulants of the topological charge in the large N limit, which up to now remained elusive. We will present first results confirming the expected large N scaling of the...
Dr
Takashi Kaneko
(KEK)
7/29/16, 2:20 PM
We report on our study of $D$ meson semileptonic decays
in 2+1 flavor lattice QCD. Gauge ensembles are generated
at the lattice cutoffs around 2.5 GeV and above
and at pion masses as low as 300 MeV. We employ
the Moebius domain-wall action for both light
and charm quarks. We report our preliminary results for
the vector and scalar form factors.
Prof.
Noriyoshi Ishii
(Research Center for Nuclear Physics (RCNP), Osaka University)
7/29/16, 2:20 PM
Nucleon-Nucleon interaction plays an essential role in nuclear
physics. In the same way, hyperon-hyperon interactions should play an
important role in hyper nuclear physics. However, unlike the nucleons
which are quite stable, hyperons decay quickly so that the direct
scattering experiments are difficult. As a result, phenomenological
determination of hyperon potentials...
Dr
Maxwell Hansen
(University of Mainz)
7/29/16, 2:20 PM
Excited-state contamination is one of the dominant uncertainties in lattice calculations of nucleon charges and form factors. To estimate this uncertainty one needs the finite-volume energy spectrum as well as the finite-volume matrix elements that determine the coefficients of excited state exponentials. In this work we use experimental data, supplemented by chiral perturbation theory (ChPT),...
Mr
Davide De Boni
(Swansea University)
7/29/16, 2:20 PM
At zero temperature nucleons and their parity partners have non-degenerate
masses due to spontaneous breaking of chiral symmetry.
However, chiral symmetry is expected to be restored at sufficiently high temperature,
in particular when going from the hadronic to the quark-gluon plasma (QGP) phase,
implying that the parity partners should become degenerate.
We study the nucleon (spin 1/2)...
Dr
Wynne Evans
(University of Bern)
7/29/16, 2:20 PM
CP(N-1) quantum field theories in (1+1)-d share important features with (3+1)-d QCD, such as asymptotic freedom, a dynamically generated mass gap and topological sectors. In the low energy limit the (2+1)-d SU(3) spin system undergoes spontaneous symmetry breaking and hence dimensional reduction to the (1+1)-d CP(2) model. By performing Monte Carlo simulations of (2+1)-d SU(3) spin systems at...
Miguel Francisco Garcia Vera
(NIC, DESY & Humboldt Universitat zu Berlin)
7/29/16, 2:20 PM
We present a precise computation of the topological susceptibility $\chi$ of SU($N$) Yang–Mills theory in the large-$N$ limit. The computation is done on the lattice, using high-statistics Monte Carlo simulations of the SU($N$) Yang-Mills theories, with $N=3, 4, 5, 6$ and three different lattice spacings. Two major improvements allowed us to go to finer lattice spacing and larger $N$ compared...
Dr
Kenji Sasaki
(Kyoto University)
7/29/16, 2:40 PM
Baryon interactions are crucial to study a bound and/or resonance state in multi-baryon systems.
In spite of their importance, phenomenological baryon potentials have large uncertainties because of the lack of experimental scattering data.
In recent studies, the HAL QCD method allow us to extract baryon interactions from the Nambu-Bethe-Salpeter wave functions without using experimental...
Mr
Junpei Kakazu
(University of Tsukuba)
7/29/16, 2:40 PM
We present preliminary result of the electromagnetic form factor of the pion
at $m_\pi=0.145$ GeV on the large volume corresponding to $L = 8.1$ fm
using stout-smearing Wilson clover quark action and Iwasaki
gauge action at $a^{-1}=2.333$ GeV. The mean square charge radius
is estimated from the results at small space-like momentum transfer
with the NLO formula in SU(2) chiral perturbation...
Giorgio Salerno
(Università di Roma Tre)
7/29/16, 2:40 PM
We present lattice results of the form factors relevant for semileptonic $D\to\pi \ell \nu$ decays, using the gauge ensembles produced by the European Twisted Mass Collaboration with Nf=2+1+1 flavors of dynamical quarks, at three values of the lattice spacing and pion masses as low as 210 MeV.
We have computed the matrix elements of both the vector and scalar weak currents for several...
Dr
Jong-Wan Lee
(Swansea University)
7/29/16, 2:40 PM
Recently the two-color gauge theory with two flavors of fundamental fermions has received considerable attention in BSM model building, as it provides a minimal template for a composite Higgs theory that includes dark matter candidates. In this work, we consider the two-color model with two flavors of Wilson fermions at non-zero temperature. For a more reliable investigation of meson...
Mr
Vadacchino Davide
(Universita' degli Studi di Torino - INFN Torino)
7/29/16, 2:40 PM
The dual formulation of the compact U(1) lattice gauge theory in three spacetime dimensions allows to finely study the squared width and the profile of the confining fluxtube on a wide range of physical interquark distances. The results obtained in Montecarlo simulations are compared with the predictions of the effective bosonic-string model and with the dual superconductor model. While the...
Dr
Bjoern Wellegehausen
(ITP University Giessen)
7/29/16, 2:40 PM
Theoretical knowlegde about the nonperturbative aspects of the phase diagram of QCD is of utmost
importance for the design of future collider experiments or the understanding of cold and dense neutron stars.
Since lattice QCD suffers from a severe sign problem at finite density, QCD-like theories are useful to understand the phase diagram
of baryonic matter at finite density. Most...
Dr
Matteo Giordano
(Eötvös University, Budapest)
7/29/16, 3:00 PM
I discuss chiral symmetry restoration and eigenmode localisation in
finite-temperature QCD by looking at the lattice Dirac operator as a
random Hamiltonian. I will argue that the features of QCD relevant to
both phenomena are the presence of order in the Polyakov line
configuration, and the correlations that this induces between spatial
links across time slices. This ties the fate of...
Mr
Csaba Torok
(Eotvos University, Budapest)
7/29/16, 3:00 PM
We study the 1+1 dimensional nonlinear O(3) model at finite chemical potential using the complex Langevin algorithm and the worm algorithm. In the latter the sign problem is totally eliminated. We determine the range of parameters, where complex Langevin produces correct results and study whether taking the continuum limit allows the exploration of the full phase diagram of the model.
Dr
Andrea Rucci
(University of Pisa and INFN Pisa)
7/29/16, 3:00 PM
I will discuss some recent results obtained in the study of the strong quark-antiquark
interaction in the presence of intense external magnetic fields. At zero temperature
the external field induces anisotropies in the static quark potential, that affect both
the spectrum and the decays of the heavy mesons. In the quark-gluon plasma phase
the screening masses do not show significant...
Dr
Hidekatsu Nemura
(Center for Computational Sciences, University of Tsukuba)
7/29/16, 3:00 PM
We present our recent study on baryon-baryon (BB) interactions from
lattice QCD with almost physical quark masses corresponding to
$(m_\pi,m_K)\approx(146,525)$ MeV and large volume
$(La)^4=(96a)^4\approx$ (8.2 fm)$^4$. In order to make better use of
large scale computer resources, a large number of BB interactions from
NN to $\Xi\Xi$ are calculated simultaneously. In this...
Aurora Melis
(RomaTre University)
7/29/16, 3:00 PM
We present the results of a Lattice QCD determination of the heavy-light vector mesons masses and decay constants. The vector decay constants are relevant hadronic parameters that, for instance, can provide phenomenologically good descriptions of non-leptonic decay rates within the factorization approximation.
Our calculation is based on the gauge configurations generated by the European...
Mr
Bartosz Kostrzewa
(HISKP (Theory) - Universitaet Bonn)
7/29/16, 3:00 PM
We present an investigation of pion structure based on ETMC $N_f=2$ and $N_f=2+1+1$
twisted mass configurations at maximal twist. We compute
the first two moments of the quark momentum fraction of the pion and the electromagnetic form factor.
For the latter, momentum is injected using twisted boundary conditions and $F_\pi(Q^2)$ is calculated
at the physical pion mass. We find that our...
Dr
Guido Cossu
(Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh)
7/29/16, 3:20 PM
We investigate the properties of the background gauge field configurations that act as disorder for the Anderson localization mechanism in the Dirac spectrum of QCD at high temperatures. We compute the eigenmodes of the M\"obius domain-wall fermion operator on configurations generated for the $SU(3)$ gauge theory with two flavors of fermions, in the temperature range $[0.9,1.9]T_c$. We...
Prof.
Steven Gottlieb
(Indiana University)
7/29/16, 3:20 PM
We present a calculation of the form factors of the $D\to K l \nu$ and $D\to\pi l \nu$ semileptonic decays at zero momentum transfer, ultimately for the purpose of determining the CKM matrix elements $|{V_{cs}}|$ and $|{V_{cd}}|$. This work uses MILC $N_f=2+1+1$ configurations with the HISQ action for both sea quarks and valence quarks, including several physical mass ensembles and lattice...
Meinulf Goeckeler
(University of Regensburg)
7/29/16, 3:20 PM
We present preliminary results of the RQCD collaboration
for the lowest moments of the distribution amplitudes of the
rho meson obtained from simulations with 2 degenerate flavours
of clover fermions. The quark masses are chosen such that we
have rho masses below the decay threshold as well as above
threshold. Treating the rho as a stable particle, we find
results for small quark masses...
Mr
Jacob Wellnhofer
(Universität Regensburg)
7/29/16, 3:20 PM
We study scalar QCD at nonzero density in the strong coupling limit.
It has a sign problem which looks structurally similar to the one in QCD.
After introducing dual variables by integrating out the SU(3) gauge links
we find that we need at least 3 flavors for a nontrivial dependence on the
chemical potential.
In this dual representation there is no sign problem remaining.
The dual...
Dr
Michael Teper
(University of Oxford)
7/29/16, 3:20 PM
We summarise the most striking features of the spectra of closed
confining flux tubes, for the flux in the fundamental
and some other representations. We compare to recent theoretical
predictions. In $D=2+1$ we present results for the continuum string
tensions for theories ranging from SU(2) to SU(16) and we determine
the leading correction to the N-dependence of k-strings.
Prof.
Nilmani Mathur
(Tata Institute of Fundamental Research)
7/29/16, 3:40 PM
We present ground state spectra of mesons containing a charm and a
bottom quark. For the charm quark we use overlap valence quarks while a
non-relativistic formulation is utilized for the bottom quark on a
background of 2+1+1 flavor HISQ gauge configurations generated by the
MILC collaboration. We also study the ratio of leptonic decay
constants, $f_{B_c^*}/f_{B_c}$. Results are obtained...
Dr
Andreas Kronfeld
(Fermilab)
7/29/16, 3:40 PM
We present results for neutral $D$-meson mixing in 2+1-flavor lattice QCD.
We compute the matrix elements for all five operators that contribute to $D$ mixing at short distances, including those that only arise beyond the Standard Model.
We present a detailed error breakdown for all sources of statistical and systematic uncertainty and the corresponding set of correlations among the matrix...
Mr
Philipp Scior
(TU Darmstadt)
7/29/16, 3:40 PM
We study the heavy quark limit of QCD-like theories by using a three-dimensional Polyakov theory. This theory can be derived from the full QCD-like theory by a combined strong coupling and hopping expansion. In particular we investigate the cold and dense regime of the phase diagram where we expect to find the Silverblaze property realized as Bose-Einstein-condensation of diquarks or a fist...
Mr
Finn M. Stokes
(University of Adelaide)
7/29/16, 3:40 PM
Variational analysis techniques in lattice QCD are powerful tools that give access to the full spectrum of QCD. At zero momentum, these techniques are well established and can cleanly isolate energy eigenstates of either positive or negative parity.
In order to compute the form factors of a single energy eigenstate, we must perform a variational analysis at nonzero momentum. When we do this...
Dr
Leonardo Cosmai
(INFN)
7/29/16, 3:40 PM
We investigate the transverse profile of the chromoelectric field
generated by a quark-antiquark pair in the vacuum of (2+1) flavor QCD.
Monte Carlo simulations are performed adopting the HISQ/tree action
discretization, as implemented in the publicly available MILC code,
suitably modified to measure the chromoelectric field.
We work on the line of constant physics, with physical...
Dr
Daisuke Kadoh
(Keio Univ.)
7/29/16, 3:40 PM
We present a precision test of the gauge gravity duality in two-dimensional N=(8,8) SYM. We employ the Sugino lattice action to perform lattice simulations of N=(8,8) SYM at finite temperature. We show the evidence of validity of the duality conjecture by comparing lattice results with analytical predictions of the corresponding gravitational theory.
Dr
Waseem Kamleh
(University of Adelaide)
7/29/16, 4:30 PM
We reveal a fundamental connection between centre
vortices and several key features associated with dynamical
chiral symmetry breaking and quark confinement. Calculations are
performed in pure $\mathrm{SU}(3)$ gauge theory using the chiral
overlap fermion action. Starting from the original gauge field, a
vortex identification procedure yields vortex-removed and vortex-only
backgrounds....
Claude Bernard
(Washington University)
,
Javad Komijani
(Technische Universit\"at M\"unchen)
7/29/16, 4:30 PM
We present high-precision results for the decay constants $f_B$ and $f_{B_s}$ from simulations with HISQ heavy and
light valence and sea quarks. Calculations are carried out with several heavy valence-quark masses on ensembles with
2+1+1 flavors of HISQ sea quarks. We generate data at five lattice spacings with three light sea quark mass ratios,
including an approximately physical...
Phiala Shanahan
(Massachusetts Institute of Technology)
7/29/16, 4:30 PM
We present the first lattice QCD study of the double-helicity-flip leading-twist gluonic structure function ∆(x,Q2). In particular, we calculate its leading moment in a φ meson and find a robust signal. This quantity is particularly interesting since, unlike the unpolarised and helicity gluon distributions, the double-helicity-flip density is a clean measure of gluonic degrees of freedom as it...
Mr
Wolfgang Unger
(Bielefeld University)
7/29/16, 4:30 PM
Lattice QCD in the strong coupling limit with staggered quarks gives rise to a dual representation. Here, the sign problem is mild enough to study the phase diagram at finite density. In the strong coupling limit, the first order nuclear and chiral transition at low temperatures coincide due to Pauli saturation.
Away from the strong coupling limit, incorporating higher order gauge...
Dr
Michele Pepe
(INFN - Sez. Milano Bicocca - Italy)
7/29/16, 4:30 PM
The thermodynamic properties of the $SU(3)$ Yang-Mills theory are
investigated from the confining phase up to 250 $T_c$. Results for the
temperature dependence of the entropy density, energy density and pressure
are presented with an accuracy of about 0.5%. The framework of shifted
boundary conditions is considered where the entropy density is related to
the expectation value of the...
Wolfgang Soeldner
(Regensburg University)
7/29/16, 4:30 PM
We present results obtained by RQCD on various observables, obtained from simulations of $N_f=2+1$ flavours of non-perturbatively order-$a$ improved Wilson fermions, employing open boundary conditions in time, that were created within the CLS (Coordinated Lattice Simulations) effort. Configurations at five different values of the lattice spacing, ranging from 0.086 fm down to below 0.04 fm...
Dr
Nigel David Cundy
(Seoul National University)
7/29/16, 4:50 PM
In earlier work, we used a gauge independent Abelian Decomposition to show that Abelian degrees of freedom where wholly responsible for the static quark postential. The Abelian decomposition contains a Maxwell part and Topological part, whose contribution to the string tension can be analysed theoretically and numerically, and arises because of the existence of a certain type of monopole. If...
Dr
Shinji Ejiri
(Niigata University)
7/29/16, 4:50 PM
We calculate the energy gap (latent heat) and pressure gap between
the hot and cold phases of the SU(3) gauge theory at the first
order deconfining phase transition point.
We perform simulations around the phase transition point with
the lattice size in the temporal direction Nt=6, 8 and 12 and
extrapolate the results to the continuum limit.
The energy density and pressure are...
Prof.
Stefan Meinel
(University of Arizona / RIKEN BNL Research Center)
7/29/16, 4:50 PM
Experimental results for mesonic $b \to s \mu^+ \mu^-$ decays show a pattern of deviations from Standard-Model predictions. These deviations could be due to new fundamental physics or due to an insufficient understanding of hadronic effects. Complementary information on the $b \to s \mu^+ \mu^-$ transition can be obtained from $\Lambda_b$ decays. This was recently done using the process...
Dr
Elena Luschevskaya
(State Scientific Center of Russian Federation - Institute of Theoretical and Experimental Physics)
7/29/16, 4:50 PM
We explore the ground state energy of pseudoscalar charged and neutral mesons as a function of external magnetic field in SU(3) lattice gauge theory. We calculate the dipole magnetic polarizabilities and hyperpolarizabilities of charged and neutral pseudoscalar pi and K mesons. It was found that the magnetic polarizability of charged pion agrees with the experimental prediction of COMPASS...
Dr
Jangho KIM
(Fakultät für Physik, Universität Bielefeld)
7/29/16, 4:50 PM
Strong coupling lattice QCD in the dual representation allows to study the full mu-T phase diagram, due to the mildness of the sign problem. This has been done in the chiral limit. Here we extend the phase diagram to finite quark masses. We present our results on the quark mass dependence of the QCD critical end point obtained by Monte Carlo via the worm algorithm. We compare our simulations...
Prof.
Gunnar Bali
(University of Regensburg)
7/29/16, 4:50 PM
We present results obtained by RQCD on various observables, obtained from simulations of $N_f=2+1$ flavours of non-perturbatively order-$a$ improved Wilson fermions, employing open boundary conditions in time, that were created within the CLS (Coordinated Lattice Simulations) effort. Configurations at five different values of the lattice spacing, ranging from 0.086 fm down to below 0.04 fm...
Ms
Olga Soloveva
(Institute for Theoretical and Experimental Physics & National Research Nuclear University MEPhI (Moscow Engine ering Physics Institute))
7/29/16, 5:10 PM
We have explored ground state energies of the light vector mesons on the base of the $SU(3)$ lattice gauge theory. This study was performed without dynamical quarks. We have observed the energies spliting depending on the value of the spin projections on an external magnetic field. The ground state energy of neutral mesons with the $s_z = 0$ diminishes with the increase of the field, while the...
Akihiro Shibata
(Computing Research Center, KEK)
7/29/16, 5:10 PM
The dual superconductivity is a promising mechanism for quark confinement. We have presented a new formulation of the Yang-Mills theory on the lattice, that enables us to change the original non-Abelian gauge field into the new field variables such that one of them called the restricted field gives the dominant contribution to quark confinement in the gauge-independent way. We...
Robert Mawhinney
(Columbia University)
7/29/16, 5:10 PM
The RBC and UKQCD Collaborations have used 2+1 flavor
Domain Wall Fermion ensembles, generated with the Iwasaki gauge
action plus the Dislocation Suppressing Determinant Ratio (DSDR),
for a variety of calculations, including our ongoing G-parity
calculation of $K \to \pi \pi$ matrix elements. These calculations
have been done with 1/a = 1.35 GeV. With the HotQCD Collaboration,
zero and...
Mr
Edwin Lizarazo
(University of Southampton)
7/29/16, 5:10 PM
We present an update on our calculation of short distance contributions
to semi-leptonic form factors for rare $B$ decays. Results for $B_s \to
\phi \ell^+\ell^-$ at three lattice spacings of $a^-1 = 1.78$, 2.38, and
2.76 GeV are shown. Our calculations are based on RBC-UKQCD's $N_f =
2+1$ domain-wall fermion and Iwasaki gauge field ensembles. The heavy
$b$-quarks are simulated using the...
Dr
Yusuke Taniguchi
(University of Tsukuba)
7/29/16, 5:10 PM
Topological susceptibility brings important information of the QCD vacuum and
contributes to a production of the axion. The temperature dependence of the topological susceptibility plays a crucial role in its production rate in the early universe.
It is a test whether the axion can be an appropriate candidate of the dark matter.
In this talk we report our recent study on the topological...
Helvio Vairinhos
(ETH Zurich)
7/29/16, 5:10 PM
In the strong coupling limit, n-point functions in lattice QCD with staggered fermions can be rewritten exactly as traces over constrained configurations of monomers, dimers, and baryon loops covering the spacetime lattice. Worm algorithms provide efficient global sampling methods over such ensembles, and are particularly efficient in the chiral limit. We study the thermodynamics of...
Dr
Chris Bouchard
(William & Mary)
7/29/16, 5:30 PM
We report on our ongoing calculation of the $B\to\pi$ semileptonic decay form factors using NRQCD/HISQ valence quarks with MILC's $N_f=2+1$ asqtad ensembles. The use of HISQ light quarks allows simulation at large pion momenta, corresponding to $q^2\approx 0$, with controlled $(ap)^2$ errors. We perform a simultaneous chiral, continuum, and kinematic extrapolation using the Hard Pion ChPT...
Ms
Carla Marchis
(University of Graz)
7/29/16, 5:30 PM
We present a dual approach for SU(2) lattice gauge theory, i.e., an exact mapping of the partition sum to new, so-called dual variables. The dual representation is constructed by decomposing the Wilson gauge action into “abelian color cycles” (ACC), which are loops in color space around plaquettes. The ACCs are complex numbers and as such commute, such that a dual representation can be...
Mr
Christian Zimmermann
(University of Regensburg)
7/29/16, 5:30 PM
The effects of double hard interactions are no longer negligible at energy scales reached at the LHC. Double parton scattering (DPS) processes are often described by taking the product of two single parton scattering processes assuming that interference effects are very small. We calculate four point functions (4pt-functions), which appear in the the DPS cross section, employing lattice...
Valentina Forini
(Humboldt University Berlin)
7/29/16, 5:30 PM
String sigma-models relevant in AdS/CFT are highly non-trivial two-dimensional field theories whose perturbative analysis is being crucially used to verify various conjectures, among which their integrability. I will discuss significant progress on how to address the extraction of information at finite values of the string effective tension via the use of lattice-based methods.
28.
The Dark Side of the Propagators: analytical approach to QCD in the infrared of Minkowski space.
Prof.
Fabio SIRINGO
(Dipartimento di Fisica e Astronomia, Università di Catania)
7/29/16, 5:30 PM
Since most of the non-perturbative approaches to QCD rely on numerical calculations in the *Euclidean* space, many important dynamical information cannot be easily extracted because of the ill-defined problem of analytic continuation for a limited set of data points.
On the other hand, by a shift of the expansion point, a perturbative approach has been developed[1,2] that has the nice feature...
Dr
Saumen Datta
(Tata Institute of Fundamental Research)
7/29/16, 5:30 PM
We use the Wilson flow to study the deconfinement transition. We construct
renormalized observables sensitive to the deconfinement transition. In
particular, behavior of renormalized operators associated with the Polyakov
loop are investigated for both quenched and two-flavor QCD. We also
investigate the behavior of various thermodynamic quantities across the transition.
Dr
Luka Leskovec
(University of Arizona)
7/29/16, 5:50 PM
Lattice QCD calculations of radiative transitions between hadrons have in the past been limited to processes of hadrons stable under the strong interaction. Recently developed methods for $1 \to 2$ transition matrix elements in a finite volume now enable the determination of radiative decay rates of strongly unstable particles. Our lattice QCD study focuses on the process $\pi \pi \to \pi...
Dr
Debasish Banerjee
(NIC, DESY)
7/29/16, 5:50 PM
We report on a recent computation of the form factors in semi-leptonic decays of the $B_s$ using Heavy Quark Effective Theory (HQET) formalism applied on the lattice. The connection of the form factors with the 2-point and 3-point correlators on the lattice is explained, and the subsequent non-perturbative renormalization of HQET and it's matching to $N_f=2$ QCD is outlined. The results of the...
Dr
Ferenc Pittler
(Eötvös University)
7/29/16, 5:50 PM
The spectrum of the two-dimensional continuum Dirac operator in
the presence of a uniform background magnetic field consists of Landau
levels, which are degenerate and separated by gaps. On the lattice the
Landau levels are spread out by discretization artefacts, but a
remnant of their structure is clearly visible (Hofstadter butterfly).
If one switches on a non-Abelian interaction, the...
Dr
Andre Sternbeck
(University of Jena)
7/29/16, 5:50 PM
We report on new results for the triple-gluon and the quark-gluon vertex in Landau gauge. Our results are based on two-flavor and quenched lattice QCD calculations for different quark masses, lattice spacings and
volumes. We will focus on the momentum dependence of the different tensor structures.
Dr
Mateusz Koren
(NIC, DESY Zeuthen)
7/29/16, 6:10 PM
The extraction of bare ground-state matrix elements for $B_s \to K\ell\nu$ decay at 2% precision poses a significant numerical challenge. Especially the B-sector, treated in HQET, is problematic due to large contamination by excited states combined with the signal-to-noise problem. The numerical setup that we use provides access to all time separations for both the two-point and three-point...
Dr
Paulo Silva
(Center for Physics, University of Coimbra)
7/29/16, 6:10 PM
In lattice QCD the computation of one-particle irreducible (1PI) Green's functions with a large number (> 2) of legs is a challenging task. Besides tuning the lattice spacing and volume to reduce finite size effects, the problems associated with the estimation of higher order moments via Monte Carlo methods and the extraction of 1PI from complete Green's functions are limitations of the...
Dr
Antoine Gerardin
(Institute for Nuclear Physics, University of Mainz)
7/29/16, 6:10 PM
We report on the lattice QCD calculation of the $\pi^0 \to \gamma^\ast \gamma^\ast$ form factor using two flavors of O(a)-improved Wilson fermions with photon virtualities in the range $Q^2 \in [0-1.5]$~GeV$^2$. Different lattice spacings and pion masses are used to extrapolate our result to the physical point.
First, we check that our results, once extrapolated to the chiral and continuum...
Ms
Marietta Magdolna Homor
(Eotvos Lorand University)
7/29/16, 6:10 PM
Motivated by the hadronization properties of heavy-ion and p-p collisions,
we study the thermalisation properties of field theories.
First of all, we present our recent observations regarding the local energy-density
and momentum distributions in the classical Phi^4 theory.
As this theory exhibits interesting features regarding these questions,
we continue the research by the MC...
Dr
Attila Pasztor
(University of Wuppertal, for the Wuppertal-Budapest collaboration)
7/29/16, 6:10 PM
We give a preliminary estimate of the shear viscosity and the sound attenuation length in a pure SU(3) gluon plasma, using an improved anisotropic gauge action. We use Wilson-flow for anisotropy tuning, shifted boundary conditions for renormalization, and a multilevel algorithm
for the measurement of the energy-momentum tensor correlators. We also look at the continuum limit of the momenta of...
Prof.
Claudio Pica
(University of Southern Denmark)
7/30/16, 9:00 AM
After the discovery of the Higgs boson, the primary objective of the Large Hadron Collider (LHC) experiments is to identify new physics beyond the Standard Model (SM). In fact, both ATLAS and CMS are providing precision tests of the Higgs sector and tantalizing hints of new, unexpected resonances.
One of the most intriguing possibilities would be the discovery of non-perturbative phenomena...
Prof.
David Kaplan
(Institute for Nuclear Theory)
7/30/16, 10:15 AM
I review some of the different approaches that have been pursued in attempting to define chiral gauge theories on the lattice, all of which are procedures for eliminating unwanted mirror fermions from the theory. I then discuss a recently published proposal with D. Grabowska that combines domain wall fermions with gradient flow as a new idea for how to decouple the mirror fermions, and which...
Prof.
Peter Boyle
(University of Edinburgh)
7/30/16, 11:45 AM
I will discuss the evolution of architectures for QCD with a focus
on the interplay between architecture, engineering, data motion and algorithms.
I also discuss recent progress in performance programming strategies and algorithms.
