出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We calculate the critical value of the hopping parameter, kc, in Lattice QCD, up to two loops in
perturbation theory. We employ the Sheikholeslami-Wohlert (clover) improved action forWilson
fermions and the Symanzik improved gluon action for 4- and 6-link loops.
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.
Our results are polynomial in cSW (clover parameter) and cover a wide range of values for the
Symanzik coefficients ci. Furthermore, the dependence on the number of colors N and the number
of fermionic flavors Nf is shown explicitly. In order to compare our results to non perturbative
evaluations of kc coming from Monte Carlo simulations, we employ an improved perturbation
theory method applied to improved actions.
