Nonperturbative O(a) improvement of Wilson quark action in three-flavor QCD with plaquette gauge action

Abstract

We perform a nonperturbative determination of the O(a)-improvement coefficient c SW for the Wilson quark action in three-flavor QCD with the plaquette gauge action. Numerical simulations are carried out in a range of β = 12.0-5.2 on a single lattice size of 8 3 × 16 employing the Schrödinger functional setup of lattice QCD. As our main result, we obtain an interpolation formula for c SW and the critical hopping parameter K c as a function of the bare coupling. This enables us to remove the O(a) scaling violation from physical observables in future numerical simulation in the wide range of β. Our analysis with a perturbatively modified improvement condition for c SW suggests that finite volume effects in c SW are not large on the 8 3 × 16 lattice. We investigate N f dependence of c SW by additional simulations for N f = 4, 2, and 0 at β = 9.6. As a preparatory step for this study, we also determine c SW in two-flavor QCD at β = 5.2. At this β, several groups have carried out large-scale calculations of the hadron spectrum, while no systematic determination of c SW has been performed. ©2005 The American Physical Society.