The effect of tree-level and mean-field improvement on the light-hadron spectrum in quenched QCD
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We compute the light hadron mass spectrum at beta=5.7 using the O(a) improved Sheikholeslami-Wohlert (SW) fermion action with two choices of the clover coefficient: the classical value, c=1, and a mean-field or tadpole-improved estimate c=1.57. We compare our results with those of the GF11 Collaboration who use the Wilson fermion action (c=0). We find that changing c from zero to 1 and 1.57 leads to significant differences in the masses of the chirally extrapolated and strange pseudoscalar and vector mesons, the nucleon, the Delta, and also in the Edinburgh plot. A number of other quantities, for example m_V^2-m_PS^2, J, am_K/am_ρand am_{K^*}/am_ρdo not appear to change significantly. We also investigate the effect of changing the lattice volume from approximately (2 fm)^3 to (2.6 fm)^3. We find that the meson masses are consistent to within one standard deviation and baryon masses are consistent to within two standard deviations.
30 pages (26 pages without figures). LaTeX (2.09 compatible) Uses Revtex style files plus epsf.sty (epsf is optional, but is the default). Accepted for publication in Phys. Rev. D.. A few inaccurate statements on the clover coefficient have been corrected
30 pages (26 pages without figures). LaTeX (2.09 compatible) Uses Revtex style files plus epsf.sty (epsf is optional, but is the default). Accepted for publication in Phys. Rev. D.. A few inaccurate statements on the clover coefficient have been corrected