Spurious gauge invariance and γ5 in Dimensional Regularization
Pablo Olgoso (Padua U.)
Tuesday, 12 November 2024 at 11:15
Abstract
Dimensional regularization is arguably the most popular and efficient scheme for multi- loop calculations. Yet, when applied to chiral (gauge) theories like the Standard Model and its extensions, one is forced to deal with the infamous “γ5 problem”. The only formulation that has been demonstrated to be consistent at all orders in perturbation theory, known as Breiteinlohner-Maison-’t Hooft-Veltman scheme, is rather cumbersome because of the subsequent breaking of chiral gauge-invariance. In this talk, I will review the various strategies to overcome this problem, and in particular the one that we recently developed based on the introduction of auxiliary fields that restore a spurious version of gauge-invariance. Finally I will show how we used this technique to evaluate the symmetry-restoring counterterms at 1-loop in the most general renormalizable gauge theory with Dirac fermions and scalar fields (the Standard Model representing a particular example), and how it can be applied to other examples.