On the universal structure of Higgs amplitudes mediated by heavy particles

TL;DR

This paper demonstrates how the four-dimensional unsubtraction/loop-tree duality approach simplifies the calculation of Higgs decay and production amplitudes, providing compact, universal expressions and natural asymptotic expansions.

Contribution

It introduces a four-dimensional method for calculating Higgs amplitudes that yields universal, compact expressions and facilitates asymptotic analysis.

Findings

Unified functional structure of amplitudes regardless of loop particles

Pure four-dimensional representation without regularization artifacts

Natural derivation of low and high mass asymptotic expansions

Abstract

We describe the calculation of the one-loop corrections to $H \to \gamma \gamma$ and $g g \to H$ within the four-dimensional unsubtraction/loop-tree duality (FDU/LTD) approach. The fact that these corrections are both IR and UV finite is not enough to perform the computation without a proper regularization of the intermediate steps. We show how the FDU/LTD method unambiguously leads to the proper result with a pure four-dimensional representation of the loop amplitude. Moreover, this method allows us to obtain very compact expressions which share the same functional structure independently of the particles circulating the loop. Besides this, asymptotic expansions for the low and high mass regime naturally arise as a consequence of the smoothness of the integrands obtained to describe the amplitudes.