Search for long-lived particles in events with photons and missing energy in proton-proton collisions at sqrt(s) = 7 TeV

TL;DR

This study searches for long-lived neutralinos decaying into photons and invisible particles using CMS data, setting new limits on their mass and decay length in proton-proton collisions at 7 TeV.

Contribution

It introduces a novel search method combining missing energy and photon timing to detect long-lived neutralinos in LHC data.

Findings

No significant excess observed over background.

Lower mass limit for neutralino > 220 GeV.

Proper decay length limit > 6000 mm.

Abstract

Results are presented from a search for long-lived neutralinos decaying into a photon and an invisible particle, a signature associated with gauge-mediated supersymmetry breaking in supersymmetric models. The analysis is based on a 4.9 inverse femtobarn sample of proton-proton collisions at sqrt(s) = 7 TeV, collected with the CMS detector at the LHC. The missing transverse energy and the time of arrival of the photon at the electromagnetic calorimeter are used to search for an excess of events over the expected background. No significant excess is observed, and lower limits at the 95% confidence level are obtained on the mass of the lightest neutralino, m(neutralino) > 220 GeV (for c tau < 500 mm), as well as on the proper decay length of the lightest neutralino, c tau > 6000 mm (for m(neutralino) < 150 GeV).