The 750 GeV diphoton excess at the LHC and dark matter constraints

TL;DR

This paper investigates the 750 GeV diphoton excess at the LHC within an effective field theory framework, proposing that an invisible decay to dark matter explains the broad width, and constrains the scenario using collider and dark matter detection data.

Contribution

It introduces a dark matter decay channel to explain the broad width of the resonance and provides combined constraints from collider and dark matter experiments.

Findings

Dark matter decay channels can account for the broad width of the resonance.

Dark matter searches exclude significant parameter space explaining the excess.

The scenario is constrained by LHC, relic density, and detection experiments.

Abstract

The recent reported 750 GeV diphoton excess at the 13 TeV LHC is explained in the framework of effective field theory assuming the diphoton resonance is a scalar (pseudoscalar) particle. It is found that the large production rate and the broad width of this resonance are hard to simultaneously explain if only visible final states are considered. Therefore an invisible decay channel to dark matter (DM) is strongly favored by the diphoton excess with a broad width, given a large coupling of the new scalar to DM. We set constraints on the parameter space in this scenario using the results from LHC Run 1, DM relic density, and DM direct and indirect detection experiments. We find that the DM searches can exclude a large portion of the parameter regions accounting for the diphoton excess with a broad width.