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LHC 750 GeV Diphoton excess in a radiative seesaw model

Research paper by Shinya Kanemura, Kenji Nishiwaki, Hiroshi Okada, Yuta Orikasa, Seong Chan Park, Ryoutaro Watanabe

Indexed on: 30 Dec '15Published on: 30 Dec '15Published in: High Energy Physics - Phenomenology



Abstract

We investigate a possibility for explaining the recently announced 750 GeV diphoton excess by the ATLAS and the CMS experiments at the CERN LHC in a model with multiple doubly-charged particles, which was originally suggested for explaining tiny neutrino masses through a three-loop effect in a natural way. The enhanced radiatively generated effective coupling of a new singlet scalar $S$ with diphoton, with multiple charged particles in the loop, enlarges the production rate of $S$ in $pp \to S+X$ via photon fusion process and also the decay width $\Gamma(S \to \gamma\gamma)$ even without assuming a tree level production mechanism. Very interestingly, we find that the branching ratio $\mathcal{B}(S \to \gamma\gamma)$ is $\simeq 60\%$ fixed by quantum numbers and the model is consistent with all the constraints from $8\,\text{TeV}$ LHC data.