Search for new phenomena in photon+jet events collected in proton--proton collisions at sqrt(s) = 8 TeV with the ATLAS detector

TL;DR

This paper reports a model-independent search for new resonances in photon+jet events at the LHC, finding no significant deviations but setting exclusion limits on certain beyond Standard Model phenomena.

Contribution

It presents the first model-independent search in photon+jet events at 8 TeV with ATLAS, setting new exclusion limits on quantum black holes and excited quarks.

Findings

No significant deviations observed from background.

Excluded quantum black holes below 4.6 TeV.

Excluded excited quarks below 3.5 TeV.

Abstract

This Letter describes a model-independent search for the production of new resonances in photon + jet events using 20 inverse fb of proton--proton LHC data recorded with the ATLAS detector at a centre-of-mass energy of sqrt(s) = 8 TeV. The photon + jet mass distribution is compared to a background model fit from data; no significant deviation from the background-only hypothesis is found. Limits are set at 95% credibility level on generic Gaussian-shaped signals and two benchmark phenomena beyond the Standard Model: non-thermal quantum black holes and excited quarks. Non-thermal quantum black holes are excluded below masses of 4.6 TeV and excited quarks are excluded below masses of 3.5 TeV.