Stau with Large Mass Difference and Enhancement of the Higgs to Diphoton Decay Rate in the MSSM

TL;DR

This paper investigates how a large mass difference between staus in the MSSM affects vacuum stability and the Higgs to diphoton decay rate, revealing that significant decay rate enhancement is challenging under these conditions.

Contribution

It introduces the analysis of large stau mass differences in the MSSM as a means to relax vacuum stability constraints, a scenario not previously considered.

Findings

Large stau mass differences can relax vacuum meta-stability constraints.

Enhancement of Higgs to diphoton decay rate is limited despite relaxed stability.

Achieving around 70% enhancement is difficult with a light stau scenario.

Abstract

The ATLAS and the CMS collaborations have presented results which show an excess of the Higgs to diphoton decay channel. In the Minimal Supersymmetric Standard Model (MSSM), this situation can be achieved by a light stau and a large left-right mixing of the staus. However, this parameter region is severely constrained by vacuum stability. In order to relax the vacuum meta-stability condition, we focus on the parameter region where the mass difference between the two staus is large. This region has not been considered yet. In this paper, we show that staus with a large mass difference can relax the vacuum meta-stability condition sufficiently even if the lighter stau mass is kept light. We find that when the mass difference of two staus is large, the enhancement of the Higgs to diphoton decay rate becomes small in spite of a relaxation of the vacuum meta-stability condition. Because of this feature, an O(70)% enhancement of the Higgs to diphoton decay rate is difficult to achieve in the light stau scenario in the MSSM.