Novel kinematics from a custodially protected diphoton resonance

TL;DR

This paper proposes a custodial symmetry-based model explaining a 750 GeV diphoton resonance via vector-like quark decay, offering novel suppression mechanisms and distinctive kinematic features that align with experimental data.

Contribution

It introduces a new custodial symmetry model for diphoton resonance production, explaining suppression of certain decay channels and predicting unique cross-section ratios and kinematic signatures.

Findings

Resonance identified as an SU(2)$_R$ triplet.

Cross-section ratio can reach up to 7 between 13 TeV and 8 TeV.

Model's kinematics are consistent with experimental distributions.

Abstract

We study a simple, well-motivated model based on a custodial symmetry which describes the tree-level production of a 750 GeV diphoton resonance from a decay of a singly produced vector-like quark. The model has several novel features. The identification of the resonance as an SU(2)$_R$ triplet provides a symmetry explanation for suppression of its decays to hh, WW, and gg. Moreover, the ratio of the 13 TeV to 8 TeV cross sections can be larger than single production of a 750 GeV resonance, reaching ratios of up to 7 for TeV scale vector-like quark masses. This eliminates any tension between the results from Run I and Run II diphoton searches. Lastly, we study the kinematics of our signal and conclude that the new production mechanism is consistent with available experimental distributions in large regions of parameter space but, depending on the mass of the new vector-like quarks, can be differentiated from the background with more statistics.