Search for resonant t t-bar production in lepton+jets events in pp collisions at sqrt(s) = 7 TeV

TL;DR

This study conducts a model-independent search for heavy resonances decaying into top-antitop pairs in proton-proton collisions at 7 TeV, setting limits on various theoretical models without observing any excess events.

Contribution

It presents a combined analysis optimized for both boosted and threshold production of top-antitop resonances, providing new exclusion limits on several theoretical models.

Findings

Excluded topcolor Z' bosons below 1.49 TeV (narrow) and 2.04 TeV (wide)

Excluded Kaluza-Klein gluons below 1.82 TeV

Set upper limits on production cross sections for resonance masses above 1 TeV

Abstract

A model-independent search for the production of heavy resonances decaying into top-antitop quark pairs is presented. The search is based on events containing one lepton (muon or electron) and at least two jets selected from data samples corresponding to an integrated luminosity of 4.4-5.0 inverse femtobarns collected in pp collisions at sqrt(s) = 7 TeV. Results are presented from the combination of two dedicated searches optimized for boosted production and production at threshold. No excess of events is observed over the expected yield from the standard model processes. Topcolor Z' bosons with narrow (wide) width are excluded at 95% confidence level for masses below 1.49 (2.04) TeV and an upper limit of 0.3 (1.3) pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV. Kaluza-Klein excitations of a gluon with masses below 1.82 TeV (at 95% confidence level) in the Randall-Sundrum model are also excluded, and an upper limit of 0.7 pb or lower is set on the production cross section times branching fraction for resonance masses above 1 TeV.