Signal-background interference effects in Higgs-mediated diphoton production beyond NLO

TL;DR

This paper advances the theoretical understanding of signal-background interference in Higgs diphoton production at the LHC by providing NNLO QCD predictions and analyzing their impact on Higgs width measurements.

Contribution

It offers the first NNLO QCD estimates of interference effects in Higgs diphoton production and assesses their implications for Higgs width constraints.

Findings

Interference effects reduce the NNLO Higgs cross-section by about 1.7%.

QCD corrections significantly influence the Higgs line-shape and width extraction.

Potential to constrain Higgs width to 10-20 times the Standard Model value with current experimental resolution.

Abstract

In this paper we consider signal-background interference effects in Higgs-mediated diphoton production at the LHC. After reviewing earlier works that show how to use these effects to constrain the Higgs boson total decay width, we provide predictions beyond NLO accuracy for the interference and related observables, and study the impact of QCD radiative corrections on the Higgs width determination. In particular, we use the so-called soft-virtual approximation to estimate interference effects at NNLO in QCD. The inclusion of these effects reduce the NNLO prediction for the total Higgs cross-section in the diphoton channel by about 1.7%. We study in detail the impact of QCD corrections on the Higgs-boson line-shape and its implications for the Higgs width extraction. Assuming an experimental resolution of about 150~MeV on interference-induced modifications of the Higgs-boson line-shape, our NNLO analysis shows that one could constrain the Higgs-boson total width to about 10-20 times its Standard Model value.