Infrared subtleties and chiral vertices at NLO: an implicit regularization analysis

Abstract

We employ implicit regularization (IReg) in quark-antiquark decays of the Z, or of a scalar (CP-even or odd) boson at NLO, and compare with dimensional schemes to reveal subtleties involving infrared divergence cancellation and gamma _5-matrix issues. Besides the absence of evanescent fields in IReg, such as epsilon -scalars required in certain schemes that operate partially in the physical dimension, we verify that our procedure preserves gauge invariance in the presence of the gamma _5 matrix without requiring symmetry preserving counterterms while the amplitude is infrared finite as stated by the KLN theorem.