Eur. Phys. J. C (2014) 74: 2944
https://doi.org/10.1140/epjc/s10052-014-2944-x

Regular Article - Theoretical Physics

High-loop perturbative renormalization constants for Lattice QCD (III): three-loop quark currents for Iwasaki gauge action and Wilson fermions

¹ Dipartimento di Fisica e Scienze della Terra, Università di Parma and INFN, Gruppo Collegato di Parma, 43100 , Parma, Italy
² Bogoliubov Laboratory of Theoretical Physics, Dubna, Russia

^* e-mail: francesco.direnzo@unipr.it

Received: 7 March 2014
Accepted: 17 June 2014
Published online: 5 July 2014

Abstract

This is the third of a series of papers on three-loop computation of renormalization constants for Lattice QCD. Our main points of interest are results for the regularization defined by the Iwasaki gauge action and Wilson fermions. Our results for quark bilinears renormalized according to the RI’-MOM scheme can be compared to non-perturbative results. The latter are available for twisted mass QCD: being defined in the chiral limit, the renormalization constants must be the same. We also address more general problems. In particular, we discuss a few methodological issues connected to summing the perturbative series such as the effectiveness of boosted perturbation theory and the disentanglement of irrelevant and finite-volume contributions. Discussing these issues we consider not only the new results of this paper, but also those for the regularization defined by the tree-level Symanzik improved gauge action and Wilson fermions, which we presented in a recent paper of ours. We finally comment on the extent to which the techniques we put at work in the NSPT context can provide a fresher look into the lattice version of the RI’-MOM scheme.