Higgs boson decay into gluons in a 4D regularization: IR cancellation without evanescent fields to NLO

Abstract

Higgs decay using an effective Higgs-Yang-Mills interaction in terms of a dimension five operator as well as usual QCD interactions is revisited in the context of Implicit Regularization (IReg) and compared with conventional dimensional regularization (CDR), four dimensional helicity (FDH) and dimensional reduction (DRED) schemes. The decay rate for $H \rightarrow gg(g)$ is calculated in this strictly four-dimensional set-up to $\alpha_s^3$ order in the strong coupling. Moreover we include joint processes that contribute at the same perturbative order in the real emission channels consisting of 3 gluons as well as gluon quark-antiquark final states with light (zero mass) quarks. Unambiguous identification and separation of UV from IR divergences is achieved putting at work the renormalization group scale relation inherent to the method. UV singularities are removed as usual by renormalization, the IR divergences are cancelled due to the method's compliance with the Kinoshita-Lee-Nauenberg (KLN) theorem. Most importantly, we verify that no evanescent fields such as $\epsilon$-scalars need be introduced as required by some mixed regularizations that operate partially in the physical dimension.