Implications of a nonvanishing $Z \gamma \gamma$ vertex on the $H\to \gamma \gamma \gamma$ decay

TL;DR

This paper explores the potential for the Higgs boson to decay into three photons via a nonstandard Z gamma gamma vertex, estimating an extremely rare branching ratio under new physics assumptions.

Contribution

It introduces a method to estimate the Higgs to three photons decay rate based on a hypothetical nonvanishing Z gamma gamma vertex induced by new physics.

Findings

Estimated BR(H→γγγ) ≲ 10^{-7}

Derived from Z→γγ and H→γZ decay channels

Provides a potential signature for new physics beyond the Standard Model

Abstract

The $Z\to \gamma \gamma$ and $H\to \gamma \gamma \gamma$ decays are strictly forbidden in the Standard Model, but they can be induced by theories that violate Lorentz symmetry or the CPT theorem. By assuming that a nonvanishing $Z\gamma \gamma$ vertex is induced in some context of new physics, and by analyzing the reaction $H\to \gamma Z^*\to \gamma \gamma \gamma$ in the $Z$ resonance, we obtain an estimation for the branching ratio of the $H\to \gamma \gamma \gamma$ decay. Specifically, it is found that $BR(H\to \gamma \gamma \gamma)\lesssim BR(H\to \gamma Z)BR_{Exp}(Z\to \gamma \gamma)$, which is of the order of $10^{-7}$.