The 750 GeV excess from photon-photon and quark-quark processes

TL;DR

This paper proposes a model explaining the 750 GeV diphoton excess at the LHC using a photonphilic scalar from Bekenstein's varying electromagnetic coupling framework, with specific production and decay channels.

Contribution

It introduces a minimal scalar model with two parameters that accounts for the excess and predicts distinctive decay signatures for experimental verification.

Findings

The scalar explains the 750 GeV excess via quark-quark and photon-photon fusion.

The model predicts a large three-body decay involving a fermion pair and a photon.

The parameters are fixed by the observed excess and suggest new search channels.

Abstract

The observed excess in the diphoton mass spectrum around 750 GeV at the 13 TeV LHC possibly indicates the presence of a photonphilic resonance. We show that the excess can be explained by a scalar of the type involved in Bekenstein's framework for varying electromagnetic coupling theories. The scalar, in our model, couples dominantly to photons and is mainly produced by the quark-quark fusion at the LHC. In addition, it can also be produced in photon-photon fusion. Our model has only two free parameters, the mass of the scalar and the scale of the new physics, which are fixed by the LHC excess to 750 GeV and 1.5 - 2 TeV, respectively. The scalar has a large three-body decay to a fermion pair and a photon, which provides an interesting search channel with a dilepton-photon resonance around 750 GeV.