Shigemi Ohta

Physical results from 2+1 flavor domain wall QCD and SU(2) chiral perturbation theory

We have simulated QCD using 2+1 flavors of domain wall quarks on a (2.74fm)3 volume with an inverse lattice scale of a?1=1.729(28) GeV. The up and down (light) quarks are degenerate in our calculations and we have used four values for the ratio of light quark masses to the strange (heavy) quark mass in our simulations: 0.217, 0.350, 0.617 and 0.884. We have measured pseudoscalar meson masses and decay constants, the kaon bag parameter BK and vector meson couplings. We have used SU(2) chiral perturbation theory, which assumes only the up and down quark masses are small, and SU(3) chiral perturbation theory to extrapolate to the physical values for the light quark masses. While next-to-leading order formulae from both approaches fit our data for light quarks, we find the higher order corrections for SU(3) very large, making such fits unreliable. We also find that SU(3) does not fit our data when the quark masses are near the physical strange quark mass. Thus, we rely on SU(2) chiral perturbation theory for accurate results. We use the masses of the ? baryon, and the ? and K mesons to set the lattice scale and determine the quark masses. We then find f?=124.1(3.6)stat(6.9)systMeV, fK=149.6(3.6)stat(6.3)systMeV and fK/f?=1.205(0.018)stat(0.062)syst. Using non-perturbative renormalization to relate lattice regularized quark masses to RI-MOM masses, and perturbation theory to relate these to MS¯ we find mMS¯ud(2GeV)=3.72(0.16)stat(0.33)ren(0.18)systMeV and mMS¯s(2GeV)=107.3(4.4)stat(9.7)ren(4.9)systMeV.

Continuum limit physics from 2+1 flavor domain wall QCD

We present physical results obtained from simulations usin g 2+1 flavors of domain wall quarks and the Iwasaki gauge action at two values of the lattice spac ing a, (a−1= 1.73 (3) GeV and a−1= 2.28 (3) GeV). On the coarser lattice, with 24 3×64×16 points (where the 16 corresponds to Ls, the extent of the 5 th dimension inherent in the domain wall fermion (DWF) formula tion

Domain wall QCD with physical quark masses

We present results for several light hadronic quantities ( f π , f K , B K , m ud , m s , t 0 ½, w 0 ) obtained from simulations of 2+1 flavor domain wall lattice QCD with large physical volumes and nearly physical pion masses at two lattice spacings. We perform a short, O (3) %, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum “global fit” with a number of other ensembles with heavier pion masses. We use the physical values of m π , m K and m Ω to determine the two quark masses and the scale—all other quantities are outputs from our simulations. We obtain results with subpercent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including f π = 130.2(9) MeV; f K = 155.5(8) MeV; the average up/down quark mass and strange quark mass in the ‾MS scheme at 3 GeV, 2.997(49) and 81.64(1.17) MeV respectively; and the neutral kaon mixing parameter, B K , in the renormalization group invariant scheme, 0.750(15) and the ‾MS scheme at 3 GeV, 0.530(11).

Kaon matrix elements and CP violation from quenched lattice QCD: 1. The three flavor case

We report the results of a calculation of the K --> pi pi matrix elements relevant for the

2 + 1 flavor domain wall QCD on a (2 fm)3 lattice : Light meson spectroscopy with Ls = 16

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Nucleon axial charge in 2+1 flavor dynamical lattice QCD with domain wall fermions

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Overview of the QCDSP and QCDOC computers

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Lattice QCD with two dynamical flavors of domain wall fermions

in quenched lattice QCD using domain wall fermions at a fixed lattice spacing

Neutral-Kaon Mixing from (2 + 1)-Flavor Domain-Wall QCD

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Domain wall fermions with improved gauge actions

GeV. Working in the three-quark effective theory, where only the u, d and s quarks enter and which is known perturbatively to next-to-leading order, we calculate the lattice K --> pi and K --> |0> matrix elements of dimension six, four-fermion operators. Through lowest order chiral perturbation theory these yield K --> pi pi matrix elements, which we then normalize to continuum values through a non-perturbative renormalization technique. For the ratio of isospin amplitudes |A_0|/|A_2| we find a value of