Search for narrow resonances in dilepton mass spectra in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports a search for high-mass narrow resonances decaying into dilepton pairs in proton-proton collisions at 7 TeV, setting new mass limits on various theoretical particles with the CMS detector.

Contribution

First search for narrow dilepton resonances at 7 TeV with CMS, providing the most stringent mass limits to date for several models.

Findings

No significant excess observed over standard model backgrounds.

Set 95% CL mass limits: 2330 GeV for Z' (SSM), 2000 GeV for Z'(psi), 890 GeV for Z'(St), 2140 GeV for Kaluza-Klein gravitons.

Results constrain new physics models predicting dilepton resonances.

Abstract

A search for narrow, high-mass resonances decaying to electron or muon pairs has been performed using pp collision data collected at sqrt(s) = 7 TeV by the CMS experiment in 2011. The data sample corresponds to an integrated luminosity of approximately 5 inverse femtobarns. The event yields observed in the signal regions are consistent with predictions of the standard model backgrounds, and upper limits on the cross section times branching fraction for a resonance decaying to dileptons are extracted from a shape analysis of the dilepton invariant mass distribution. The resulting mass limits at 95% confidence level are 2330 GeV for the Z' in the Sequential Standard Model, 2000 GeV for the superstring-inspired Z'(psi) resonance, 890 (540) GeV for the Stueckelberg extension Z'(St) with the mass parameter epsilon = 0.06 (0.04), and 2140 (1810) GeV for Kaluza--Klein gravitons with the coupling parameter k/Mbar(Pl) of 0.10 (0.05). These limits are the most stringent to date.