Gauge invariance at work in FDR: H -> gamma gamma

TL;DR

This paper demonstrates that the Four Dimensional Regularization scheme (FDR) can accurately compute the Higgs to two photons decay amplitude while preserving gauge invariance, matching results from traditional dimensional regularization.

Contribution

It provides the first complete FDR calculation of a physical process, confirming FDR's gauge invariance and consistency with established methods.

Findings

FDR yields the same result as dimensional regularization for H -> gamma gamma.

FDR is a gauge-invariant, 4-dimensional regularization technique.

The calculation confirms FDR's validity in realistic scenarios.

Abstract

We present the first complete calculation performed within the Four Dimensional Regularization scheme (FDR), namely the loop-induced on-shell amplitude for the Higgs boson decay into two photons in an arbitrary R_csi gauge. FDR is a new technique -free of infinities- for addressing multi-loop calculus, which automatically preserves gauge invariance, allowing for a 4-dimensional computation at the same time. We obtained the same result as that assessed in dimensional regularization, thereby explicitly verifying, in a realistic case, that FDR respects gauge invariance.