The force awakens - the 750 GeV diphoton excess at the LHC from a varying electromagnetic coupling

Authors: Ulf Danielsson, Rikard Enberg, Gunnar Ingelman and Tanumoy Mandal

Preprint number: UUITP-01/16

We show that the recent 750 GeV diphoton excess observed at the LHC may be explained by the production of a scalar of the type involved in Bekenstein's framework for varying-alpha theories, with the difference that the scalar in our model has a large mass. The model has only two free parameters, the mass of the scalar and the scale of this new physics, which are fixed by the LHC excess to 750 GeV and 3-4 TeV, respectively. We discuss collider and cosmology aspects of the model, and give predictions for future LHC searches. In particular, the scalar is dominantly produced by quark-antiquark fusion in association with a photon or a fermion pair. In addition, it can be produced in the s-channel in photon-photon fusion. Its dominating decay is to diphotons, but it also has a large three-body decay to a fermion pair and a photon, which provides an interesting search channel with a dilepton-photon resonance at 750 GeV. We also comment on the possibility that the new physics is related to extra dimensions or string theory.