Search for new phenomena in monophoton final states in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This study searches for new physics signals in monophoton final states at the LHC, setting new limits on dark matter, extra dimensions, and branon production, with no deviations from the standard model observed.

Contribution

First LHC limits on branon production in monophoton events, extending previous bounds from LEP and Tevatron, using 8 TeV proton-proton collision data.

Findings

No deviation from standard model predictions.

Set upper limit of 14.0 fb on monophoton cross section.

Established new constraints on dark matter and extra-dimensional models.

Abstract

Results are presented from a search for new physics in final states containing a photon and missing transverse momentum. The data correspond to an integrated luminosity of 19.6 inverse femtobarns collected in proton-proton collisions at sqrt(s) = 8 TeV with the CMS experiment at the CERN LHC. No deviation from the standard model predictions is observed for these final states. New, improved limits are set on dark matter production and on parameters of models with large extra dimensions. In particular, the first limits from the LHC on branon production are found and significantly extend previous limits from LEP and the Tevatron. An upper limit of 14.0 fb on the cross section is set at the 95% confidence level for events with a monophoton final state with photon transverse momentum greater than 145 GeV and missing transverse momentum greater than 140 GeV.