Search for excited quarks in the photon+jet final state in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a search for excited quarks decaying into photon+jet final states using 8 TeV proton-proton collision data, setting mass exclusion limits up to 3.5 TeV.

Contribution

First search for excited quarks in photon+jet final states at 8 TeV with CMS, establishing new mass exclusion limits.

Findings

Excluded excited quark masses below 3.5 TeV at 95% CL.

Set upper limits on production cross section and branching ratios.

No significant resonance observed in photon+jet invariant mass spectrum.

Abstract

A search for excited quarks decaying into the photon+jet final state is presented. The analysis is based on data corresponding to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS experiment in proton-proton collisions at sqrt(s) = 8 TeV at the LHC. Events with photons and jets with high transverse momenta are selected and the photon+jet invariant mass distribution is studied to search for a resonance peak. The 95% confidence level upper limits on the product of cross section and branching fraction are evaluated as a function of the excited quark mass. Limits on excited quarks are presented as a function of their mass and coupling strength; masses below 3.5 TeV are excluded at 95% confidence level for unit couplings to their standard model partners.