Hyperon vector coupling f_1(0) from 2+1 flavor lattice QCD

We present results for the hyperon vector form factor f_1 for $\Xi^0 \rightarrow \Sigma^+ l\bar{\nu}$ and $\Sigma^- \rightarrow n l\bar{\nu}$ semileptonic decays from dynamical lattice QCD with domain-wall quarks. Simulations are performed on the 2+1 flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice cutoff of 1/a = 1.7 GeV. Our preliminary results, which are calculated at the lightest sea quark mass (pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on hyperon vector coupling f_1(0) is likely negative.Comment: 4 pages, 2 figures, talk given at International Conference on the Structure of Baryons (BARYONS'10), Osaka, Japan, Dec. 7-11, 201

The parity partner of the nucleon in quenched QCD with domain wall fermions

We present preliminary results for the mass spectrum of the nucleon and its low-lying excited states from quenched lattice QCD using the domain wall fermion method which preserves the chiral symmetry at finite lattice cutoff. Definite mass splitting is observed between the nucleon and its parity partner. This splitting grows with decreasing valence quark mass. We also present preliminary data regarding the first positive-parity excited state.Comment: LATTICE99(QCD spectrum), Latex with espcrc2.sty, 3 pages, 3 figures, RBRC preprin

Lattice study of nucleon properties with domain wall fermions

Domain wall fermions (DWF) are a new fermion discretization scheme with greatly improved chiral symmetry. Our final goal is to study the nucleon spin structure through lattice simulation using DWF. In this paper, we present our current progress on two topics toward this goal: 1) the mass spectrum of the nucleon excited states and 2) the iso-vector vector and axial charges, $g_{V}$ and $g_{A}$, of the nucleon.Comment: 8 pages, LaTeX with ws-p8-50x6-00.cls, 6 figures (6 eps files), Talk given at NSTAR2001, University of Mainz, Germany, March 7-10, 2001. To be published by World Scientifi

Latest results from lattice QCD for the Roper resonance

The present status of the Roper resonance in lattice QCD is reviewed. Some of the latest lattice results are discussed with particular emphasis on a large systematic error stemming from the finite size effect. These results suggest that the Roper resonance can be described by the simple three quark excitation of sizable extent.Comment: 6 pages, 6 figures, to appear in Prog. Theor. Phys. Suppl. in the proceedings of the Tokyo - Adelaide Joint Workshop on Quarks, Astrophysics and Space Physics, minor typos correcte

Potential description of the charmonium from lattice QCD

We present spin-independent and spin-spin interquark potentials for charmonium states, that are calculated using a relativistic heavy quark action for charm quarks on the PACS-CS gauge configurations generated with the Iwasaki gauge action and 2+1 flavors of Wilson clover quark. The interquark potential with finite quark masses is defined through the equal-time Bethe-Salpeter amplitude. The light and strange quark masses are close to the physical point where the pion mass corresponds to $M_\pi \approx 156(7)$ MeV, and charm quark mass is tuned to reproduce the experimental values of $\eta_c$ and $J/\psi$ states. Our simulations are performed with a lattice cutoff of $a^{-1}\approx 2.2$ GeV and a spatial volume of $(3 {\rm fm})^3$. We solve the nonrelativistic Schr\"odinger equation with resulting charmonium potentials as theoretical inputs. The resultant charmonium spectrum below the open charm threshold shows a fairly good agreement with experimental data of well-established charmonium states.Comment: 12 pages, 4 figures, the Proceedings of the Conference "XIth Quark Confinement and the Hadron Spectrum", September 8 to 12, Saint-Petersburg State University, Russi