Di-photon Higgs Decay in SUSY with CP Violation

TL;DR

This paper investigates how CP violation in the MSSM affects the di-photon decay of the lightest Higgs, highlighting the significant influence of a light stop on decay width and branching ratio.

Contribution

It introduces an analysis of Higgs-sfermion couplings' effects on di-photon decay, extending previous studies focused solely on scalar/pseudo-scalar mixing.

Findings

A light stop can significantly alter the decay width and BR of H1 --> gamma.gamma.

Large CP-violating phase can increase the di-photon BR by over 50%.

Other light sparticles have minimal impact on the decay process.

Abstract

Physical Higgs particles in the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation are CP mixed states. The decay of these Higgs particles can be analysed to study the CP properties of the MSSM. In the present work we consider the di-photon channel of the lightest neutral Higgs boson for this purpose. Compared to earlier studies on effects of scalar/pseudo-scalar mixing, our analysis also investigates the effect due to Higgs-sfermion-sfermion couplings along with that of mixing. We find that a light stop may have a strong impact on the width and Branching Ratio (BR) of the decay process H1 --> gamma.gamma, whereas other light sparticles have only little influence. In some regions of the MSSM parameter space with large CP-violating phase phi-mu ~ 90 deg a light (~ 200 GeV) stop can change the di-photon BR by more than 50 % compared to the case with heavy (~ 1 TeV) stop and otherwise same MSSM parameters.