Minimal Composite Dynamics versus Axion Origin of the Diphoton excess

TL;DR

This paper explores a minimal composite model and an axion-based interpretation for the 750 GeV diphoton excess, proposing ways to distinguish between these scenarios and test composite dynamics through topological processes.

Contribution

It introduces a simple pseudoscalar model that explains the diphoton excess and provides methods to differentiate between axion and composite state origins.

Findings

The model can accommodate the observed diphoton excess.

Distinctive signatures allow testing of composite dynamics.

Possible future observations can confirm or refute the scenarios.

Abstract

ATLAS and CMS observe deviations from the expected background in the diphoton invariant mass searches of new resonances around 750 GeV. We show that a simple realization in terms of a new pseudoscalar state can accommodate the observations. The model leads to further footprints that can be soon observed. The new state can be interpreted both as an axion or as a {highly natural} composite state arising from minimal models of dynamical electroweak symmetry breaking. We further show how to disentangle the two scenarios. Beyond the possible explanation of the diphoton excess the results show that it is possible to directly test and constrain composite dynamics via processes stemming from its distinctive topological sector.