# HEP/Astro Journal Club -- Friday, 25 January 2002

##
The 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
to non perturbative evaluations of `κ`_{c}
coming from Monte Carlo simulations.

## Reference

H. Panagopoulos and Y. Proestos, *“The critical hopping parameter
in *`O`(`a`) improved lattice QCD,”
Phys. Rev. D **65**, 014511 (2002)
[hep-lat/0108021].

## 12:30, Smith Lab 4079

George T. Fleming
(
gfleming@mps.ohio-state.edu
),
last updated 11 January 2002.