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Dr
Renwick J. Hudspith
(York University)
25/07/2016, 14:15
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Anthony Francis
(York University)
25/07/2016, 14:35
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Gavin Cheung
(University of Cambridge)
25/07/2016, 14:55
Hadron Spectroscopy and Interactions
Talk
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...
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Prof.
Pedro Bicudo
(Universidade de Lisboa)
25/07/2016, 15:15
Hadron Spectroscopy and Interactions
Talk
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...
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Ms
Antje Peters
(Goethe-Universität Frankfurt am Main)
25/07/2016, 15:35
Hadron Spectroscopy and Interactions
Talk
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.
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Mr
Ryutaro Fukuda
(University of Tokyo, RIKEN BNL Research Center)
25/07/2016, 15:55
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Joshua Berlin
(University of Frankfurt)
25/07/2016, 16:45
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Jacob Finkenrath
(german)
25/07/2016, 17:05
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Tobias Neitzel
(Goethe University Frankfurt)
25/07/2016, 17:25
Hadron Spectroscopy and Interactions
Talk
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...
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Prof.
Francesco Knechtli
(University of Wuppertal)
25/07/2016, 17:45
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Ciaran Hughes
(University of Cambridge)
25/07/2016, 18:05
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Cian O'Hara
(Trinity College Dublin)
25/07/2016, 18:25
Hadron Spectroscopy and Interactions
Talk
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...
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Markus Werner
(University of Bonn)
26/07/2016, 14:00
Hadron Spectroscopy and Interactions
Talk
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.
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Mr
Bin Hu
(Department of Physics, The George Washington University)
26/07/2016, 14:20
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Antoni Woss
(University of Cambridge)
26/07/2016, 14:40
Hadron Spectroscopy and Interactions
Talk
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...
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Christian Rohrhofer
(University of Graz)
26/07/2016, 15:00
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Raul Briceno
(Thomas Jefferson National Accelerator Facillity)
26/07/2016, 15:20
Hadron Spectroscopy and Interactions
Talk
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...
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Prof.
Stephen Sharpe
(University of Washington)
26/07/2016, 15:40
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Christopher Helmes
(HISKP Universität Bonn)
26/07/2016, 16:30
Hadron Spectroscopy and Interactions
Talk
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....
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Jozef Dudek
(Jefferson Lab)
26/07/2016, 16:50
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Liuming Liu
(University of Bonn)
26/07/2016, 17:10
Hadron Spectroscopy and Interactions
Talk
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...
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Sasa Prelovsek
(University of Ljubljana)
26/07/2016, 17:30
Hadron Spectroscopy and Interactions
Talk
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.
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Prof.
Ying Chen
(Institute of High Energy Physics, CAS)
26/07/2016, 17:50
Hadron Spectroscopy and Interactions
Talk
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....
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Yusuke Namekawa
(University of Tsukuba)
28/07/2016, 14:00
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
David Tims
(Trinity College Dublin)
28/07/2016, 14:20
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Tomasz Korzec
(Bergische Universität Wuppertal)
28/07/2016, 14:40
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Graham Moir
(University of Cambridge)
28/07/2016, 15:00
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Christopher Thomas
(University of Cambridge)
28/07/2016, 15:20
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Antonio Cox
(University of Regensburg)
28/07/2016, 15:40
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Takumi Iritani
(Stony Brook University)
28/07/2016, 16:30
Hadron Spectroscopy and Interactions
Talk
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...
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Prof.
Sinya Aoki
(Yukawa Institute for Theoretical Physics, Kyoto University)
28/07/2016, 16:50
Hadron Spectroscopy and Interactions
Talk
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...
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Takeshi Yamazaki
(Univ. of Tsukuba)
28/07/2016, 17:10
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Takuya Sugiura
(RCNP, Osaka University)
28/07/2016, 17:30
Hadron Spectroscopy and Interactions
Talk
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...
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Mr
Takaya for HAL QCD Collaboration Miyamoto
(Yukawa Institute for Theoretical Physics, Kyoto University)
28/07/2016, 17:50
Hadron Spectroscopy and Interactions
Talk
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...
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Daisuke KAWAI
(Kyoto University)
28/07/2016, 18:10
Hadron Spectroscopy and Interactions
Talk
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...
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Doi Takumi
(RIKEN)
29/07/2016, 14:00
Hadron Spectroscopy and Interactions
Talk
The lattice QCD determination of baryon interactions corresponds to connecting a missing link between particle physics and nuclear and astrophysics. While previous studies are limited to the calculations with unphysically heavy quark masses, we are performing the first calculation employing the (almost) physical quark masses (m(pi) = 146 MeV) on a huge lattice volume of (8fm)^4, where the...
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Prof.
Noriyoshi Ishii
(Research Center for Nuclear Physics (RCNP), Osaka University)
29/07/2016, 14:20
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Kenji Sasaki
(Kyoto University)
29/07/2016, 14:40
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Hidekatsu Nemura
(Center for Computational Sciences, University of Tsukuba)
29/07/2016, 15:00
Hadron Spectroscopy and Interactions
Talk
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...
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Dr
Brendan Fahy
(KEK)
29/07/2016, 15:20
Hadron Spectroscopy and Interactions
Talk
We explore the properties of heavy-light psuedoscalar mesons above the
charm mass sing Mobius domain-wall fermions on fine lattices at a~0.080,
0.055, and 0.044 fm. We examine masses and decay constants using a
series of heavy quark masses up to 3 times the charm quark. We attempt
to analyze the cutoff effects for heavy quarks above the charm and
account for the low order effects using...
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Prof.
Nilmani Mathur
(Tata Institute of Fundamental Research)
29/07/2016, 15:40
Hadron Spectroscopy and Interactions
Talk
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...
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Wolfgang Soeldner
(Regensburg University)
29/07/2016, 16:30
Hadron Spectroscopy and Interactions
Talk
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...
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Prof.
Gunnar Bali
(University of Regensburg)
29/07/2016, 16:50
Hadron Spectroscopy and Interactions
Talk
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...
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Robert Mawhinney
(Columbia University)
29/07/2016, 17:10
Hadron Spectroscopy and Interactions
Talk
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...
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