Critical hopping parameter in O(a) improved lattice QCD

Abstract

We calculate the critical value of the hopping parameter, κ c, in O(a) improved lattice QCD, to two loops in perturbation theory. We employ the Sheikholeslami-Wohlert (clover) improved action for Wilson fermions. The quantity which we study is a typical case.of a vacuum expectation value resulting in an additive renormalization

as such, it is characterized by a power (linear) divergence in the lattice spacing, and its calculation lies at the limits of applicability of perturbation theory. The dependence of our results on the number of colors N, the number of fermionic flavors, N f, and the clover parameter c sw is shown explicitly. We compare our results with nonperturbative evaluations of κ c coming from Monte Carlo simulations. © 2001 The American Physical Society.