CP Violation in Higgs Diphoton Decay in Models with Vectorlike Heavy Fermions

TL;DR

This paper explores how models with heavy vectorlike fermions can induce CP violation in Higgs diphoton decay, suggesting experimental methods to detect such effects through photon conversion measurements.

Contribution

It demonstrates that heavy vectorlike fermions can generate sizable CP-odd contributions to Higgs diphoton decay amplitude, proposing an experimental approach to observe CP violation.

Findings

CP violation can arise from complex phases in heavy fermion mass matrices.

Measurement of photon conversion angles can reveal CP-odd effects.

Experimental feasibility of detecting CP violation in Higgs decay is discussed.

Abstract

The amplitude of the diphoton decay of the Higgs boson is considered in an extension of the Standard Model involving heavy vectorlike fermions, which was recently suggested in the literature in order to explain a possible enhancement of the h -> gamma gamma decay rate. It is pointed out that generally in such models the decay amplitude acquires a sizable CP-odd contribution from the complex phases in the mass matrix of the new heavy fermions. The resulting CP violation in the diphoton decay can be studied experimentally when both photons are converted into e^+ e^- pairs by measuring the distribution over the angle between the planes of the pairs. Such measurement, if feasible, would be of a great interest on its own, regardless specific models.