Conveners
Nonzero Temperature and Density
- Gergely Endrodi (University of Frankfurt)
Nonzero Temperature and Density
- Kazuyuki Kanaya (CiRfSE, Univ. Tsukuba)
Nonzero Temperature and Density
- Christian Schmidt (Universitaet Bielefeld)
Nonzero Temperature and Density
- Francesco Di Renzo (University of Parma & INFN)
Nonzero Temperature and Density
- Jaeger Benjamin (Swansea University)
Nonzero Temperature and Density
- Denes Sexty (Uni Wuppertal)
Nonzero Temperature and Density
- Edwin Laermann (Bielefeld University)
Nonzero Temperature and Density
- Falk Bruckmann (University of Regensburg)
Nonzero Temperature and Density
- Alexander Rothkopf (Institute for Theoretical Physics, Heidelberg University)
Nonzero Temperature and Density
- Philippe de Forcrand (ETH Zurich & CERN)
Nonzero Temperature and Density
- Jacques Bloch (University of Regensburg)
Nonzero Temperature and Density
- Kalman Szabo (Forschungszentrum Juelich)
Kalman Szabo
(U Wuppertal, FZ Juelich)
25/07/2016, 14:15
Nonzero Temperature and Density
Talk
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.
Prof.
Sandor Katz Katz
(Eotvos University, Budapest)
25/07/2016, 14:35
Nonzero Temperature and Density
Talk
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.
Dr
Szabolcs Borsanyi
(University of Wuppertal)
25/07/2016, 14:55
Nonzero Temperature and Density
Talk
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)
25/07/2016, 15:15
Nonzero Temperature and Density
Talk
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
Yoshifumi Nakamura
(RIKEN)
25/07/2016, 15:35
Nonzero Temperature and Density
Talk
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...
Edwin Laermann
(Bielefeld University)
25/07/2016, 15:55
Nonzero Temperature and Density
Talk
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
Christopher Czaban
(Goethe University Frankfurt am Main)
25/07/2016, 16:45
Nonzero Temperature and Density
Talk
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...
Mr
Alessandro Sciarra
(Goethe Universität)
25/07/2016, 17:05
Nonzero Temperature and Density
Talk
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...
Ms
Francesca Cuteri
(Goethe University - Frankfurt)
25/07/2016, 17:25
Nonzero Temperature and Density
Talk
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...
Dr
Kouji Kashiwa
(Yukawa Institute for Theoretical Physics, Kyoto University)
25/07/2016, 17:45
Nonzero Temperature and Density
Talk
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...
Mr
Michele Mesiti
(University of Pisa and INFN - Sezione di Pisa)
25/07/2016, 18:05
Nonzero Temperature and Density
Talk
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...
Prof.
Christian Fischer
(JLU Giessen)
25/07/2016, 18:25
Nonzero Temperature and Density
Talk
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
Felipe Attanasio
(Swansea University)
26/07/2016, 14:00
Nonzero Temperature and Density
Talk
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...
Dr
Benjamin Jaeger
(Swansea University)
26/07/2016, 14:20
Nonzero Temperature and Density
Talk
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...
Dr
Nicolas Garron
(PU)
26/07/2016, 14:40
Nonzero Temperature and Density
Talk
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
Mario Giuliani
(University of Graz)
26/07/2016, 15:00
Nonzero Temperature and Density
Talk
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...
Dr
Savvas Zafeiropoulos
(Goethe University Frankfurt)
26/07/2016, 15:20
Nonzero Temperature and Density
Talk
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...
Dr
Yuta Ito
(KEK)
26/07/2016, 15:40
Nonzero Temperature and Density
Talk
In many interesting systems, the fermion determinant becomes complex and its phase plays a crucial role in the determination of the vacuum. For instance, in finite density QCD at low temperature and high density, exotic fermion condensates are conjectured to form due to such effects. When one applies the complex Langevin method to such a complex action system naively, one cannot obtain the...
Dr
Donald SInclair
(Argonne-Seville)
26/07/2016, 16:30
Nonzero Temperature and Density
Talk
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.
Prof.
Gert Aarts
(Swansea University)
26/07/2016, 16:50
Nonzero Temperature and Density
Talk
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...
Dr
Denes Sexty
(Uni Wuppertal)
26/07/2016, 17:10
Nonzero Temperature and Density
Talk
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...
Shinji Shimasaki
(Keio University)
26/07/2016, 17:30
Nonzero Temperature and Density
Talk
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...
Dr
Keitaro Nagata
(KEK)
26/07/2016, 17:50
Nonzero Temperature and Density
Talk
The complex Langevin method is a promising approach
to complex action systems, which suffer from the sign problem.
In particular, the use of gauge cooling enabled the studies of finite
density QCD either in the deconfined phase or in the heavy dense limit.
In the confined phase with light quarks, however, the method does not
work as it is due to the singularities in the fermion drift...
Dr
Jacques Bloch
(University of Regensburg)
26/07/2016, 18:10
Nonzero Temperature and Density
Talk
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
Christian Schmidt
(Universitaet Bielefeld)
27/07/2016, 09:00
Nonzero Temperature and Density
Talk
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...
Dr
Yuya Tanizaki
(RIKEN BNL Research Center)
27/07/2016, 09:20
Nonzero Temperature and Density
Talk
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
Francesco Di Renzo
(University of Parma & INFN)
27/07/2016, 10:00
Nonzero Temperature and Density
Talk
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...
Dr
Hiromichi Nishimura
(RIKEN BNL Research Center)
27/07/2016, 10:20
Nonzero Temperature and Density
Talk
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...
Asobu Suzuki
(University of Tsukuba)
27/07/2016, 10:40
Nonzero Temperature and Density
Talk
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...
Prof.
Kazuyuki Kanaya
(CiRfSE, Univ. Tsukuba)
27/07/2016, 11:30
Nonzero Temperature and Density
Talk
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...
Ms
Jana Günther
(University of Wuppertal)
27/07/2016, 11:50
Nonzero Temperature and Density
Talk
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...
Dr
Falk Bruckmann
(University of Regensburg)
27/07/2016, 12:10
Nonzero Temperature and Density
Talk
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...
Dr
Jon-Ivar Skullerud
(Maynooth University)
28/07/2016, 14:00
Nonzero Temperature and Density
Talk
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 $T_c$.
Mr
Atsuro Ikeda
(Osaka University)
28/07/2016, 14:20
Nonzero Temperature and Density
Talk
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
Haitao Shu
(CCNU)
28/07/2016, 14:40
Nonzero Temperature and Density
Talk
The spectral functions provide us the knowledge to understand the in-medium hadron and transport properties of the QCD medium. For instance, quantities like thermal dilepton production and photon emission rates of QGP can be obtained from the vector spectral functions. Though spectral functions are important, they can not be obtained directly from Euclidean lattice QCD calculations. Analytic...
Dr
Hiroshi Ohno
(University of Tsukuba)
28/07/2016, 15:00
Nonzero Temperature and Density
Talk
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
Alexander Rothkopf
(Institute for Theoretical Physics, Heidelberg University)
28/07/2016, 15:20
Nonzero Temperature and Density
Talk
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...
Mr
Aman Steinberg
(Uni Mainz)
28/07/2016, 15:40
Nonzero Temperature and Density
Talk
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
Gergely Endrodi
(University of Frankfurt)
28/07/2016, 16:30
Nonzero Temperature and Density
Talk
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
Bastian Brandt
(University of Frankfurt)
28/07/2016, 16:50
Nonzero Temperature and Density
Talk
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...
Mr
Aleksandr Nikolaev
(ITEP)
28/07/2016, 17:10
Nonzero Temperature and Density
Talk
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...
Mr
Lukas Holicki
(Justus-Liebig-University Giessen)
28/07/2016, 17:30
Nonzero Temperature and Density
Talk
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...
Mr
Bardiya Bahrampour
(Justus-Liebig University Giessen)
28/07/2016, 17:50
Nonzero Temperature and Density
Talk
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
Jeffrey Greensite
(San Francisco State University)
28/07/2016, 18:10
Nonzero Temperature and Density
Talk
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
Tobias Rindlisbacher
(ETH Zürich)
29/07/2016, 14:00
Nonzero Temperature and Density
Talk
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)
29/07/2016, 14:00
Nonzero Temperature and Density
Talk
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
Davide De Boni
(Swansea University)
29/07/2016, 14:20
Nonzero Temperature and Density
Talk
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)
29/07/2016, 14:20
Nonzero Temperature and Density
Talk
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...
Dr
Jong-Wan Lee
(Swansea University)
29/07/2016, 14:40
Nonzero Temperature and Density
Talk
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...
Dr
Bjoern Wellegehausen
(ITP University Giessen)
29/07/2016, 14:40
Nonzero Temperature and Density
Talk
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)
29/07/2016, 15:00
Nonzero Temperature and Density
Talk
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)
29/07/2016, 15:00
Nonzero Temperature and Density
Talk
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
Guido Cossu
(Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh)
29/07/2016, 15:20
Nonzero Temperature and Density
Talk
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...
Mr
Jacob Wellnhofer
(Universität Regensburg)
29/07/2016, 15:20
Nonzero Temperature and Density
Talk
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...
Mr
Philipp Scior
(TU Darmstadt)
29/07/2016, 15:40
Nonzero Temperature and Density
Talk
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...
Dr
Daisuke Kadoh
(Keio Univ.)
29/07/2016, 15:40
Nonzero Temperature and Density
Talk
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.
Mr
Wolfgang Unger
(Bielefeld University)
29/07/2016, 16:30
Nonzero Temperature and Density
Talk
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)
29/07/2016, 16:30
Nonzero Temperature and Density
Talk
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...
Dr
Shinji Ejiri
(Niigata University)
29/07/2016, 16:50
Nonzero Temperature and Density
Talk
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...
Dr
Jangho KIM
(Fakultät für Physik, Universität Bielefeld)
29/07/2016, 16:50
Nonzero Temperature and Density
Talk
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...
Dr
Yusuke Taniguchi
(University of Tsukuba)
29/07/2016, 17:10
Nonzero Temperature and Density
Talk
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)
29/07/2016, 17:10
Nonzero Temperature and Density
Talk
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...
Ms
Carla Marchis
(University of Graz)
29/07/2016, 17:30
Nonzero Temperature and Density
Talk
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...
Dr
Saumen Datta
(Tata Institute of Fundamental Research)
29/07/2016, 17:30
Nonzero Temperature and Density
Talk
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
Ferenc Pittler
(Eötvös University)
29/07/2016, 17:50
Nonzero Temperature and Density
Talk
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
Victor Braguta
(ITEP)
29/07/2016, 17:50
Nonzero Temperature and Density
Talk
This report is devoted to the study of temperature dependence of shear viscosity in SU(3)-gluodynamics.
To calculate shear viscosity we measured the correlation function of the energy-momentum tensor
T_{12}T_{12} for a set of temperatures in the region T/T_c \in (0.9, 1.5). The measurements
were carried out using multilevel algorithm which considerably improves the accuracy
of the...
Ms
Marietta Magdolna Homor
(Eotvos Lorand University)
29/07/2016, 18:10
Nonzero Temperature and Density
Talk
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)
29/07/2016, 18:10
Nonzero Temperature and Density
Talk
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...
