h → γγ in U(1)R -lepton number model with a right-handed neutrino

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 provides an additional tree level contribution to the lightest Higgs boson mass along with a very light (mass similar to 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 total decay width of the Higgs boson and its various branching fractions are affected. When studied in conjunction with the recent LHC results, these put significant constraints on the parameter space. 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. Because of the absence of a light neutralino, the total decay width of the lightest Higgs boson in this case remains close to the SM expectation. Hence, in the small 'f' scenario we obtain a relatively larger value of mu (gamma gamma) which is closer to the central values reported recently by these two collaborations.