Symmetries and composite dynamics for the 750 GeV diphoton excess

TL;DR

This paper explores theoretical models involving symmetries and composite dynamics to explain the 750 GeV diphoton excess observed at the LHC, proposing new particle spectra and production mechanisms.

Contribution

It introduces two scenarios with nearly parity degenerate and vector-scalar degenerate spectra, motivated by dynamical models of electroweak symmetry breaking, to explain the excess.

Findings

Proposes pseudo-scalar production via gluon or photon fusion.

Analyzes decay of a parent particle with soft final states.

Discusses underlying realizations without new coloured states.

Abstract

The ATLAS and CMS experiments at LHC observe small excesses of diphoton events with invariant mass around 750 GeV. Here we study the possibility of nearly parity degenerate and vector-scalar degenerate spectra as well as composite dynamics in 2 scenarios for explaining the excess: Production of a pseudo-scalar via gluon or photon fusion or via decay of a parent particle together with soft additional final states. We discuss possible underlying realizations of the scenarios motivated by dynamical models of electroweak symmetry breaking (without new coloured states) and fermion masses.