858 research outputs found

    Lattice study of nucleon properties with domain wall fermions

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    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, gVg_{V} and gAg_{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

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

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    We present results for the hyperon vector form factor f_1 for Ξ0→Σ+lνˉ\Xi^0 \rightarrow \Sigma^+ l\bar{\nu} and Σ−→nlνˉ\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

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    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

    Hyperon vector form factor from 2+1 flavor lattice QCD

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    We present the first result for the hyperon vector form factor f_1 for Xi^0 -> Sigma^+ l bar{nu} and Sigma^- -> n l bar{nu} semileptonic decays from fully dynamical lattice QCD. The calculations are carried out with gauge configurations generated by the RBC and UKQCD collaborations with (2+1)-flavors of dynamical domain-wall fermions and the Iwasaki gauge action at beta=2.13, corresponding to a cutoff 1/a=1.73 GeV. Our results, which are calculated at the lighter three sea quark masses (the lightest pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on the hyperon vector coupling f_1(0) is negative. The tendency of the SU(3) breaking correction observed in this work disagrees with predictions of both the latest baryon chiral perturbation theory result and large N_c analysis.Comment: 7 pages, 12 figures, v2: typos corrected, and references added, v3: version published in PR

    Latest results from lattice QCD for the Roper resonance

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    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
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