17121387
2+1 Flavor Lattice QCD with Luescher's Domain-Decomposed HMC Algorithm
We report on a study of 2+1 flavor lattice QCD with the $O(a)$-improved Wilson quarks on a $16^3\times 32$ lattice at the lattice spacing $1/a\approx 2$GeV employing Luescher's domain-decomposed HMC(LDDHMC) algorithm. This is dedicated to a preliminary study for the PACS-CS project which plans to complete the Wilson-clover $N_f=2+1$ program lowering the up-down quark masses close to the physical values as much as possible. We focus on three issues: (i) how light quark masses we can reach with LDDHMC, (ii) efficiency of the algorithm compared with the conventional HMC, (iii) parameter choice for the production runs on PACS-CS.
119237422
One-loop operator matching in the static heavy and domain-wall light quark system with O(a) improvement
We discuss perturbative O(g2a) matching with static heavy quarks and domain-wall light quarks for lattice operators relevant to B-meson decays and $ {B^0} - {\bar{B}^0} $ mixing. The chiral symmetry of the light domain-wall quarks does not prohibit operator mixing at O(a) for these operators. The O(a) corrections to physical quantities are non-negligible and must be included to obtain high-precision simulation results for CKM physics. We provide results using plaquette, Symanzik, Iwasaki and DBW2 gluon actions and applying APE, HYP1 and HYP2 link-smearing for the static quark action.
117535752
Improving chiral property of domain-wall fermions by reweighting method
The reweighting method is applied to improve the chiral property of domain-wall fermions. One way to achieve this is to enlarge L{sub s}, the size of fifth dimension, which controls the size of the induced chiral symmetry breaking. While this is a type of reweighting method for shifting the action parameter, it seems non-trivial since this reweighting means change of the five dimensional lattice volume. In this report, we address issues in this direction of reweighting and evaluate its effectiveness.
119107424
Neutral $B$ meson mixings and $B$ meson decay constants with static heavy and domain-wall light quarks
Neutral $B$ meson mixing matrix elements and $B$ meson decay constants are calculated. Static approximation is used for $b$ quark and domain-wall fermion formalism is employed for light quarks. The calculations are carried out on $2+1$ flavor dynamical ensembles generated by RBC/UKQCD Collaborations with lattice spacings $0.086$fm ($a^{-1}\sim 2.3$GeV) and $0.11$fm ($1.7$GeV), and a fixed physical spatial volume of about $(2.7{\rm fm})^3$. In the static quark action, link-smearings are used to improve the signal-to-noise ratio. We employ two kinds of link-smearings, HYP1 and HYP2, and their results are combined in taking the continuum limit. For the matching between the lattice and the continuum theory, one-loop perturbative $O(a)$ improvements are made to reduce discretization errors. As the most important quantity of this work, we obtain SU(3) breaking ratio $\xi=1.208(60)$, where the error includes statistical and systematic one. (Uncertainty from infinite $b$ quark mass is not included.) We also find other neutral $B$ meson mixing quantities $f_B\sqrt{\hat{B}_B}=240(22)$MeV, $f_{B_s}\sqrt{\hat{B}_{B_s}}=290(22)$MeV, $\hat{B}_B=1.17(22)$, $\hat{B}_{B_s}=1.22(13)$ and $B_{B_s}/B_B=1.028(74)$, $B$ meson decay constants $f_B=219(17)$MeV, $f_{B_s}=264(19)$MeV and $f_{B_s}/f_B=1.193(41)$, in the static limit of $b$ quark, which do not include infinite $b$ quark mass uncertainty.
117986111
An estimate of the eta and eta-prime meson masses in Nf=2+1 lattice QCD
Masses of the eta and eta-prime mesons are estimated in Nf=2+1 lattice QCD with the non-perturbatively O(a) improved Wilson quark action and the Iwasaki RG-improved gluon action, using CP-PACS/JLQCD configurations on a 16^3 x 32 lattice at beta=1.83 (lattice spacing is 0.122 fm). We apply a stochastic noise estimator technique combined with smearing method to evaluate correlators among flavor SU(2) singlet pseudoscalar operators and strange pseudoscalar operators for 10 combinations of up/down and strange quark masses. The correlator matrix is then diagonalized to identify signals for mass eigenstates. Masses of the ground state and the first excited state extrapolated to the physical point are m_eta= 0.545(16) GeV and m_eta-prime= 0.871(46) GeV, being close to the experimental values of the eta and eta-prime masses.
17179550
Quenched Scaling Study of Charm and Bottom Systems with a Relativistic Heavy Quark Action
CP-PACS Collaborations: Y. Kuramashi∗a,b †, S. Aokib,c, O. Bärb, K.-I. Ishikawag, T. Ishikawaa, N. Ishizukaa,b, Y. Iwasakib, K. Kanayab, T. Kanekoe, f , M. Okawag, Y. Taniguchia,b, N. Tsutsuie, A. Ukawaa,b, N. Yamadae and T. Yoshiéa,b a Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan b Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan c Riken BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973, USA d Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582, Japan e High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan f School of High Energy Accelerator Science, The Graduate University for Advanced Studies (Sokendai), Tsukuba 305-0801, Japan g Department of Physics, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
9121234
A Feynman graph selection tool in GRACE system
We present a Feynman graph selection tool grcsel, which is an interpreter written in C language. In the framework of GRACE, it enables us to get a subset of Feynman graphs according to given conditions.