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Title: Effects of staggered fermions and mixed actions on the scalar correlator

Abstract

We provide the analytic predictions for the flavor nonsinglet scalar correlator, which will enable determination of the scalar meson mass from the lattice scalar correlator. We consider simulations with 2+1 staggered sea quarks and staggered or chiral valence quarks. At small u/d masses the correlator is dominated by the bubble contribution, which is the intermediate state with two pseudoscalar mesons. We determine the bubble contribution within staggered and mixed chiral perturbation theory. Its effective mass is smaller than the mass of {pi}{eta}, which is the lightest intermediate state in proper 2+1 QCD. The unphysical effective mass is a consequence of the taste breaking that makes possible the intermediate state with mass 2M{sub {pi}}. We find that the scalar correlator can be negative in the simulations with mixed quark actions if the sea- and valence-quark masses are tuned by matching the pion masses M{sub val,val}=M{sub {pi}{sub 5}}.

Authors:
 [1]
  1. Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia) and Institute Jozef Stefan, Jamova 39, 1000 Ljubljana (Slovenia)
Publication Date:
OSTI Identifier:
20774618
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 73; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevD.73.014506; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACTION INTEGRAL; CHIRAL SYMMETRY; CHIRALITY; COMPUTERIZED SIMULATION; EFFECTIVE MASS; FLAVOR MODEL; INTERMEDIATE STATE; LATTICE FIELD THEORY; PERTURBATION THEORY; PIONS; QUANTUM CHROMODYNAMICS; QUARKS; SCALAR MESONS; SCALARS; VALENCE

Citation Formats

Prelovsek, S. Effects of staggered fermions and mixed actions on the scalar correlator. United States: N. p., 2006. Web. doi:10.1103/PhysRevD.73.014506.
Prelovsek, S. Effects of staggered fermions and mixed actions on the scalar correlator. United States. doi:10.1103/PhysRevD.73.014506.
Prelovsek, S. Sun . "Effects of staggered fermions and mixed actions on the scalar correlator". United States. doi:10.1103/PhysRevD.73.014506.
@article{osti_20774618,
title = {Effects of staggered fermions and mixed actions on the scalar correlator},
author = {Prelovsek, S.},
abstractNote = {We provide the analytic predictions for the flavor nonsinglet scalar correlator, which will enable determination of the scalar meson mass from the lattice scalar correlator. We consider simulations with 2+1 staggered sea quarks and staggered or chiral valence quarks. At small u/d masses the correlator is dominated by the bubble contribution, which is the intermediate state with two pseudoscalar mesons. We determine the bubble contribution within staggered and mixed chiral perturbation theory. Its effective mass is smaller than the mass of {pi}{eta}, which is the lightest intermediate state in proper 2+1 QCD. The unphysical effective mass is a consequence of the taste breaking that makes possible the intermediate state with mass 2M{sub {pi}}. We find that the scalar correlator can be negative in the simulations with mixed quark actions if the sea- and valence-quark masses are tuned by matching the pion masses M{sub val,val}=M{sub {pi}{sub 5}}.},
doi = {10.1103/PhysRevD.73.014506},
journal = {Physical Review. D, Particles Fields},
number = 1,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • We study discretization effects in a mixed-action lattice theory with domain-wall valence quarks and Asqtad-improved staggered sea quarks. At the level of the chiral effective Lagrangian, discretization effects in the mixed-action theory give rise to two new parameters as compared to the lowest order Lagrangian for rooted-staggered fermions - the residual quark mass m{sub res} and the mixed valence-sea meson mass splitting {delta}{sub mix}. We find that m{sub res}, which parametrizes explicit chiral symmetry breaking in the mixed-action theory, is approximately one-quarter the size of our lightest valence quark mass on our coarser lattice spacing and of comparable size tomore » that of simulations by the RBC and UKQCD Collaborations. We also find that the size of {delta}{sub mix} is comparable to the size of the smallest of the staggered meson taste splittings measured by the MILC Collaboration. Because lattice artifacts are different in the valence and sea sectors of the mixed-action theory, they give rise to unitarity-violating effects that disappear in the continuum limit, some of which should be described by mixed-action chiral perturbation theory (MA{chi}PT). Such effects are expected to be mild for many quantities of interest but are expected to be significant in the case of the isovector scalar (a{sub 0}) correlator. Specifically, once the parameters m{sub res}, {delta}{sub mix}, and two others that can be determined from the light pseudoscalar meson spectrum are known, the two-particle intermediate state 'bubble' contribution to the scalar correlator is completely predicted within MA{chi}PT. We find that the behavior of the scalar meson correlator is quantitatively consistent with the MA{chi}PT prediction; this supports the claim that MA{chi}PT describes the dominant unitarity-violating effects in the mixed-action theory and can therefore be used to remove lattice artifacts and recover physical quantities.« less
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