Calculation of the One W Loop $H \to \gamma \gamma$ Decay Amplitude with a Lattice Regulator

TL;DR

This paper performs a lattice-regulated perturbative calculation of the Higgs to two photon decay amplitude, confirming the standard result and addressing recent controversy over regularization methods.

Contribution

It introduces a lattice regulator approach to compute the $H o \gamma \gamma$ decay amplitude, providing a gauge-invariant alternative to dimensional regularization.

Findings

Lattice and dimensional regularization results agree within high statistical accuracy.

The lattice approach confirms the standard decay amplitude calculation.

Addresses controversy over regularization methods in Higgs decay calculations.

Abstract

There has been a controversial recent claim that the standard result on the Higgs to two photon decay rate is incorrect, with the use of dimensional regularization fingered as the alleged culprit. Given the great importance of the $H\to \gamma \gamma$ process as a possible Standard Model Higgs discovery channel at the LHC if the Higgs mass is light, it is critical to find a way to check the correctness of the results of dimensional regularization for this process. Here we report the results of a perturbative calculation of the $H\to \gamma \gamma$ decay amplitude using a spacetime lattice as a UV regulator, which is the only known gauge-invariant regulator for non-Abelian gauge theories other than dimensional regularization. We find that the decay amplitude calculated using lattice-regularized perturbation theory is consistent to very high statistical accuracy with the decay amplitude obtained using dimensional regularization.