Light staus and enhanced Higgs diphoton rate with non-universal gaugino masses and SO(10) Yukawa unification

TL;DR

This paper explores how non-universal gaugino masses at the GUT scale can enhance the Higgs to diphoton decay rate in the MSSM, consistent with Yukawa unification and phenomenological constraints.

Contribution

It identifies specific gaugino mass patterns that enhance the Higgs diphoton rate while satisfying Yukawa unification and phenomenological bounds, including scenarios with non-universal soft terms.

Findings

Higgs to diphoton rate can be increased by up to 30%

Light sbottom and pseudoscalar Higgs are accessible at 14 TeV LHC

Dark matter relic abundance can be compatible with bino-like LSP via stau coannihilation

Abstract

It is shown that substantially enhanced Higgs to diphoton rate induced by light staus with large left-right mixing in MSSM requires at the GUT scale non-universal gaugino masses with bino and/or wino lighter than gluino. The possibility of such enhancement is investigated in MSSM models with arbitrary gaugino masses at the GUT scale with additional restriction of top-bottom-tau Yukawa unification, as predicted by minimal SO(10) GUTs. Many patterns of gaugino masses leading to enhanced Higgs to diphoton rate and the Yukawa unification are identified. Some of these patterns can be accommodated in a well-motivated scenarios such as mirage mediation or SUSY breaking F-terms being a non-singlet of SO(10). Phenomenological implications of a scenario with non-universal gaugino masses generated by a mixture of the singlet F-term and the F-term in a 24-dimensional representation of SU(5) $\subset$ SO(10) are studied in detail. Possible non-universalities of other soft terms generated by such F-terms are discussed. The enhancement of Higgs to diphoton rate up to 30% can be obtained in agreement with all phenomenological constraints, including vacuum metastability bounds. The lightest sbottom and pseudoscalar Higgs are within easy reach of the 14 TeV LHC. The LSP can be either bino-like or wino-like. The thermal relic abundance in the former case may be in agreement with the cosmological data thanks to efficient stau coannihilation.