$h \rightarrow \gamma \gamma$ in $U(1)_{R}-$ lepton number model with a right-handed neutrino

TL;DR

This paper investigates the Higgs to diphoton signal in a $U(1)_R$ lepton number model with a right-handed neutrino, exploring how neutrino Yukawa coupling affects Higgs phenomenology and dark matter implications.

Contribution

It provides a detailed analysis of the Higgs diphoton signal in this specific model, considering the effects of neutrino Yukawa coupling and light neutralinos on Higgs decay and dark matter.

Findings

The Higgs diphoton signal rate is compatible with LHC results for large neutrino Yukawa coupling.

A small Yukawa coupling allows for a sterile neutrino dark matter candidate explaining X-ray observations.

The model predicts a light neutralino and neutrino mass consistent with experimental constraints.

Abstract

We perform a detailed study of the signal rate of the lightest Higgs boson in the diphoton channel ($\mu_{\gamma \gamma}$), recently analyzed by both the ATLAS and CMS collaborations at the Large Hadron Collider, in the framework of $U(1)_R-$ lepton number model with a right handed neutrino superfield. The corresponding neutrino Yukawa coupling, `$f$', plays a very important role in the phenomenology of this model. A large value of $f\sim\mathcal O(1)$ provides an additional tree level contribution to the lightest Higgs boson mass along with a very light (mass $\sim$ a few hundred MeV) bino like neutralino and a small tree level mass of one of the active neutrinos that is compatible with various experimental results. In the presence of this light neutralino, the invisible decay width of the Higgs boson can become important. We studied this scenario in conjunction with the recent LHC results. The signal rate $\mu_{\gamma\gamma}$ obtained in this scenario is compatible with the recent results from both the ATLAS and the CMS collaborations at 1$\sigma$ level. A small value of `$f$', on the other hand, is compatible with a sterile neutrino acting as a 7 keV dark matter that can explain the observation of a mono-energetic X-ray photon line by the XMM-Newton X-ray observatory. We also study the impact of $\mu_{\gamma\gamma}$ in this case.