Search for new phenomena in high-mass diphoton final states using 37 fb$^{-1}$ of proton-proton collisions collected at $\sqrt{s}=13$ TeV with the ATLAS detector

TL;DR

This paper reports a search for new high-mass phenomena in diphoton final states using 37 fb$^{-1}$ of proton-proton collision data at 13 TeV with the ATLAS detector, finding no significant deviations from the Standard Model.

Contribution

It presents the first search for both resonant and non-resonant new phenomena in high-mass diphoton events at 13 TeV with detailed limits set on various models.

Findings

No significant excess observed over the Standard Model predictions.

Upper limits set on production cross sections for potential new resonances.

Lower limits established on the ultraviolet cutoff scale in large extra-dimension models.

Abstract

Searches for new phenomena in high-mass diphoton final states with the ATLAS experiment at the LHC are presented. The analysis is based on $pp$ collision data corresponding to an integrated luminosity of 36.7 fb$^{-1}$ at a centre-of-mass energy $\sqrt{s}=13$ TeV recorded in 2015 and 2016. Searches are performed for resonances with spin 0, as predicted by theories with an extended Higgs sector, and for resonances with spin 2, using a warped extra-dimension model as a benchmark model, as well as for non-resonant signals, assuming a large extra-dimension scenario. No significant deviation from the Standard Model is observed. Upper limits are placed on the production cross section times branching ratio to two photons as a function of the resonance mass. In addition, lower limits are set on the ultraviolet cutoff scale in the large extra-dimensions model.