Shoji Hashimoto

Comparative study of the full QCD hadron spectrum and the static quark potential with improved actions

We investigate the effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for

Nonperturbative O(a) improvement of the Wilson quark action with the renormalization-group-improved gauge action using the Schrödinger functional method

{a}^{ensuremath{-}1}ensuremath{approx}1 mathrm{GeV}

Light hadron spectrum in three-flavor QCD with O(a)-improved Wilson quark action

and

Nucleon axial and tensor charges with dynamical overlap quarks

{m}_{mathrm{PS}}{/m}_{mathrm{V}}=0.7char21{}0.9

Pion form factors in two-flavor QCD

. We compare a renormalization group improved action with the plaquette action for gluons and the SW-clover action with the Wilson action for quarks. We find a significant improvement in the hadron spectrum by improving the quark action, while the gluon improvement is crucial for a rotationally invariant static potential. We also explore the region of light quark masses corresponding to

Study of finite volume effects in the non-perturbative determination of cSW with the SF method in full three-flavor lattice QCD

{m}_{mathrm{PS}}{/m}_{mathrm{V}}g~0.4

Overlap/Domain-wall reweighting

on a 2.7 fm lattice using the improved gauge and quark action. A flattening of the potential is not observed up to 2 fm.

Non-perturbative determination ofcsw in three-flavor dynamical QCD

We perform a nonperturbative determination of the O(a)-improvement coefficient c{sub SW} and the critical hopping parameter {kappa}{sub c} for N{sub f}=3, 2, and 0 flavor QCD with the (RG) renormalization-group-improved gauge action using the Schroedinger functional method. In order to interpolate c{sub SW} and {kappa}{sub c} as a function of the bare coupling, a wide range of {beta} from the weak coupling region to the moderately strong coupling points used in large-scale simulations is studied. Corrections at finite lattice size of O(a/L) turned out to be large for the RG-improved gauge action, and hence we make the determination at a size fixed in physical units using a modified improvement condition. This enables us to avoid O(a) scaling violations which would remain in physical observables if c{sub SW} determined for a fixed lattice size L/a is used in numerical simulations.

Analysis of topological structure of the QCD vacuum with overlap-Dirac operator eigenmode

Abstract We report on a calculation of the light hadron spectrum and quark masses in three-flavor dynamical QCD using the non-perturbatively O(a)-improved Wilson quark action and a renormalization-group improved gauge action. Simulations are carried out on a 163 × 32 lattice at β = 1.9, where a−1 ≅ 2 GeV, with 6 ud quark masses corresponding to m π m ϱ ≅ 0.64–0.77 and 2 s quark masses close to the physical value. We observe that the inclusion of dynamical strange quark brings the lattice QCD meson spectrum to good agreement with experiment. Dynamical strange quarks also lead to a reduction of the uds quark masses by about 15%.

Continuum limit of proton decay matrix elements in quenched lattice QCD

We report on our calculation of the nucleon axial and tensor charges in 2+1-flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the all-mode-averaging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the all-to-all quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses