Interpreting the 750 GeV Di-photon Resonance using photon-jets in Hidden-Valley-like models

TL;DR

This paper proposes a hidden-valley-like model where a 750 GeV scalar decays into photon-jets, explaining the di-photon resonance observed at the LHC, and discusses future experimental tests.

Contribution

It introduces a novel interpretation of the 750 GeV resonance as photon-jets from hidden particles, linking collider signals to hidden sector physics.

Findings

Photon-jets can mimic single photons in detectors.

The model explains the 750 GeV di-photon excess.

Testable predictions for LHC Run-2 are discussed.

Abstract

Motivated by the di-photon resonance recently reported by the ATLAS and CMS collaborations at $\sqrt{s} =13$ TeV, we interpret the resonance as a scalar boson $X (750)$ in hidden-valley-like models. The scalar boson $X$ can mix with the standard model Higgs boson and thus can be produced via gluon fusion. It then decays into a pair of very light hidden particles $Y$ of sub-GeV, each of which in turn decays to a pair of collimated $ \pi^{0} $'s, and these two $ \pi^{0} $'s decay into photons which then form photon-jets. A photon-jet ($ \gamma $-jet) is a special feature that consists of a cluster of collinear photons from the decay of a fast moving light particle (sub-GeV). Because these photons inside the photon-jet are so collimated that it cannot be distinguished from a single photon, and so in the final state of the decay of $X(750)$ a pair of photon-jets look like a pair of single photons, which the experimentalists observed and formed the 750 GeV di-photon resonance. Prospects for the LHC Run-2 about other new and testable features are also discussed.