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N. Ishizuka

Publications and source records attributed to N. Ishizuka.

175 records · Page 10Linked to original sources
arXiv1997

Lattice QCD Calculation of the Kaon B-parameter with the Wilson Quark Action

The kaon B parameter is calculated in quenched lattice QCD with the Wilson quark action. The mixing problem of the Δs=2 four-quark operators is solved non-perturbatively with full use of chiral Ward identities, and this method enables us to construct the weak four-quark operators exhibiting good chiral behavior. We find B_K(NDR, 2GeV)=0.562(64) in the continuum limit, which agrees with the value obtained with the Kogut-Susskind quark action.

hep-lat↗
arXiv1996

Topics in Light Hadron Mass Spectrum in Quenched QCD

Several topics concerning the light hadron spectrum are discussed. Flavor symmetry breaking effects and the problem of quenched chiral logarithm are examined with pion mass data for the Kogut-Susskind quark action, and light meson decay constants for the Wilson action calculated with non-perturbative renormalization constants are discussed. Results for quark masses are also given both for the Kogut-Susskind and Wilson actions.

hep-lat↗
arXiv1996

Continuum Limit of the Heavy-Light Decay Constant with the Quenched Wilson Quark Action

We explore the problems in calculating the decay constant for heavy-light mesons using the quenched Wilson quark action for both heavy and light quarks. We find that the continuum limit of the decay constant is reasonably converged among different prescriptions after the continuum limit is taken. A number of technical problems associated with prescriptions are also addressed.

hep-lat↗
arXiv1996

Toward the Continuum Limit of $B_K$ with the Quenched Kogut-Susskind Quark Action

We present new results of our ongoing project toward a precision determination of the kaon $B$ parameter with the Kogut-Susskind quark action in quenched QCD. New results taken at $β$=6.4 and $β=5.7$ suggest that an apparently linear $a$ dependence of $B_K$ previously observed for $β=5.85-6.2$ arises from a change of curvature from convex to concave as the lattice spacing is reduced. Fitting data for $β\geq 5.93$ with an $O(a^2)$ form yields $B_K$(NDR,2 GeV)=0.587(7)(17) in the continuum limit. We also describe a finite-size study of $B_K$ at $β=$ 6.0 and 6.4, and a reanalysis of the theoretical argument for $O(a^2)$ behavior.

hep-lat↗
arXiv1995

$f_B$ quenched and unquenched

Results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$, and their ratios are presented. High statistics quenched runs at $β=5.7$, $5.85$, $6.0$, and $6.3$, plus a run still in progress at $β=6.52$ make possible a preliminary extrapolation to the continuum. The data allows good control of all systematic errors except for quenching, although not all of the error estimates have been finalized. Results from configurations which include effects of dynamical quarks show a significant deviation from the quenched results and make possible a crude estimate of the quenching error.

hep-lat↗
arXiv1995

Status and prospect for determining $f_B$, $f_{B_s}$, $f_{B_s} / f_B$ on the lattice

Preliminary results from the MILC collaboration for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. We compute in the quenched approximation at $β=6.3$, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify all systematic errors other than quenching, and have a first indication of the size of quenching errors.

hep-ph↗
arXiv1994

Preliminary heavy-light decay constants from the MILC collaboration

Preliminary results from the MILC collaboration for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. We compute in the quenched approximation at $β=6.3$, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify systematic errors due to finite volume, finite lattice spacing, large $am$, and fitting and extrapolation uncertainties. The hopping parameter approach of Henty and Kenway is used to treat the heavy quarks; the sources are Coulomb gauge gaussians.

hep-lat↗
arXiv1994

Charmonium spectroscopy with heavy Kogut-Susskind quarks

Charmonium spectroscopy with Kogut-Susskind valence quarks are carried out for quenched QCD at $β=6.0$ and for two-flavor full QCD at $β=5.7$. Results for 1P--1S mass splitting and estimates of $α^{(5)}_{\overline{MS}}(m_Z)$ are reported. Problems associated with flavor breaking effects and finite size effects of $1P$ states are discussed.

hep-lat↗
arXiv1994

Manifestation of Sea Quark Effects in the Strong Coupling Constant in Lattice QCD

We demonstrate that sea quark effects of a magnitude expected from renormalization group considerations are clearly visible in the strong coupling constant measured in current full QCD simulations. Building on this result an estimate of $α_{\overline{MS}}^{(5)}(M_Z)$ is made employing the charmonium $1S-1P$ mass splitting calculated on full QCD configurations generated with two flavors of dynamical Kogut-Susskind quarks to fix the scale.

hep-lat↗
arXiv1993

Finite-Size Effect of Hadron Masses with Kogut-Susskind Quarks

We present numerical results and their analyses of finite-size effects of hadron masses for both quenched and full QCD calculations. We show that they are much larger for full QCD due to dynamical sea quarks and the associated breaking of $Z(3)$ symmetry. We also argue that finite-size effects are non-negligible even for the largest lattice size simulation currently being made for a very small quark mass. (talk at lattice93)

hep-lat↗
arXiv1993

Sea Quark Effects on the Strong Coupling Constant

We present results showing that the strong coupling constant measured in two-flavor full QCD with dynamical Kogut-Susskind quarks at $β=5.7$ exhibit a 15\% increase due to sea quarks over that for quenched QCD at the scale $μ\approx 7$GeV . (talk at lattice93)

hep-lat↗
arXiv1993

Perturbative renormalization factors for bilinear and four-quark operators for Kogut-Susskind fermions on the lattice

Renormalization factors for bilinear and four-quark operators with the Kogut-Susskind fermion action are perturbatively calculated to one-loop order in the general covariant gauge. Results are presented both for gauge invariant and non-invariant operators. For four-quark operators the full renormalization matrix for a complete set of operators with two types of color contraction structures are worked out and detailed numerical tables are given.

hep-lat↗