Singlet Scalar Resonances and the Diphoton Excess

TL;DR

This paper explores the possibility that a singlet scalar resonance at 750 GeV explains the diphoton excess observed by ATLAS and CMS, discussing its implications, constraints, and associated signals.

Contribution

It demonstrates that a singlet scalar can account for the diphoton excess while satisfying constraints, and discusses the challenges of explaining the large width.

Findings

A singlet scalar resonance can explain the diphoton excess.

Large total width is difficult to achieve with loop decays alone.

The model predicts a robust Z-gamma signature.

Abstract

ATLAS and CMS recently released the first results of searches for diphoton resonances in 13 TeV data, revealing a modest excess at an invariant mass of approximately 750 GeV. We find that it is generically possible that a singlet scalar resonance is the origin of the excess while avoiding all other constraints. We highlight some of the implications of this model and how compatible it is with certain features of the experimental results. In particular, we find that the very large total width of the excess is difficult to explain with loop-level decays alone, pointing to other interesting bounds and signals if this feature of the data persists. Finally we comment on the robust Z-gamma signature that will always accompany the model we investigate.