Implications of a Modified Higgs to Diphoton Decay Width

TL;DR

This paper explores how new charged particles could enhance the Higgs boson's diphoton decay width beyond Standard Model predictions, with implications for detecting new physics at the electroweak scale.

Contribution

It analyzes the potential for new charged scalars, fermions, and vector bosons to increase the diphoton decay width without affecting other Higgs channels, highlighting observable effects.

Findings

Significant diphoton width variations possible with light new particles.

Large couplings from Higgs-induced mass mixing can enhance decay width.

Correlated shifts in Z + Gamma channel can indicate new charged particles.

Abstract

Motivated by recent results from Higgs searches at the Large Hadron Collider, we consider possibilities to enhance the diphoton decay width of the Higgs boson over the Standard Model expectation, without modifying either its production rate or the partial widths in the WW and ZZ channels. Studying effects of new charged scalars, fermions and vector bosons, we find that significant variations in the diphoton width may be possible if the new particles have light masses of the order of a few hundred GeV and sizeable couplings to the Higgs boson. Such couplings could arise naturally if there is large mass mixing between two charged particles that is induced by the Higgs vacuum expectation value. In addition, there is generically also a shift in the Z + Gamma partial width, which in the case of new vector bosons tends to be of similar magnitude as the shift in the diphoton partial width, but smaller in other cases. Therefore simultaneous measurements in these two channels could reveal properties of new charged particles at the electroweak scale.