Effect of tree-level and mean-field improvement on the light-hadron spectrum in quenched QCD

Abstract

We compute the light-hadron mass spectrum at ␤ϭ5.7 using the O(a)-improved Sheikholeslami-Wohlert fermion action with two choices of the clover coefficient: the classical value cϭ1 and a mean-field or tadpole-improved estimate cϭ1.57. We compare our results with those of the GF11 Collaboration who use the Wilson fermion action (cϭ0). 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 ⌬, and also in the Edinburgh plot. A number of other quantities, for example, m V 2 Ϫm P 2 , J, am K /am , and am K* /am do not appear to change significantly. We also investigate the effect of changing the lattice volume from approximately ͑2 fm͒ 3 to ͑2.6 fm͒ 3. We find that the meson masses are consistent to within one standard deviation and baryon masses are consistent to within two standard deviations.

Non-perturbative O(a) improvement of lattice QCD

“…First steps in this direction have already been taken 28,29] and it is clear from these calculations that improvement has a signi cant impact on the hadron masses and decay constants. One would now need to check that the continuum limit is indeed reached more rapidly than in the unimproved theory.…”

Two heavy-light mesons on a lattice

“…With improved clover coefficient C SW = 1.57, we use a value of κ 1 = 0.14077 which corresponds to a bare mass of the light quark around the strange mass and gives a pseudoscalar to vector mass ratio of 0.650 (7). The chiral limit corresponds to κ c = 0.14351 [18]. Error estimates come from bootstrap over the gauge configurations.…”

Comparative study of the full QCD hadron spectrum and the static quark potential with improved actions

“…Results for the vector meson mass in the chiral limit, translated into the lattice spacing through a ρ = A V /768MeV, are listed in Table I and II. Results for the nucleon and ∆ also show curvature in terms of m PS a. We therefore fit them employing a cubic polynomial without the linear term (12) as for the vector meson mass.…”

“…Studies of improved actions have been widely pursued in the last few years. Detailed tests of improvement for the hadron spectrum, however, have been carried out mostly within quenched QCD [12][13][14][15][16][17][18][19] with only a few full QCD attempts [20][21][22]. In particular, a systematic investigation of how gauge and quark action improvement, taken separately, affects light hadron observables has not been carried out in full QCD.…”