出版社:SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要:We study a systematic improvement of perturbation theory for gauge fields on the lattice [1]; the
improvement entails resumming, to all orders in the coupling constant, a dominant subclass of
tadpole diagrams.
This method, originally proposed for the Wilson gluon action [2], is extended here to encompass
all possible gluon actions made of closed Wilson loops; any fermion action can be employed as
well. The effect of resummation is to replace various parameters in the action (coupling constant,
Symanzik and clover coefficient) by “dressed” values; the latter are solutions to certain coupled
integral equations, which are easy to solve numerically.
Some positive features of this method are: a) It is gauge invariant, b) it can be systematically
applied to improve (to all orders) results obtained at any given order in perturbation theory, c) it
does indeed absorb in the dressed parameters the bulk of tadpole contributions.
Two different applications are presented: The additive renormalization of fermion masses, and
the multiplicative renormalization ZV (ZA) of the vector (axial) current. In many cases where
non-perturbative estimates of renormalization functions are also available for comparison, the
agreement with improved perturbative results is consistently better as compared to results from
bare perturbation theory.