A search for <i>t</i>(<i>t</i>)over-bar resonances in lepton plus jets events with highly boosted top quarks collected in pp collisions at √<i>s</i>=7 TeV with the ATLAS detector


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Aad G., Abajyan T., Abbott B., Abdallah J., Abdel Khalek S., Abdelalim A., ...More

JOURNAL OF HIGH ENERGY PHYSICS, no.9, 2012 (SCI-Expanded, Scopus) identifier identifier identifier

Abstract

A search for resonant production of high-mass top-quark pairs is performed on 2.05 fb(-1) of proton-proton collisions at root s = 7 TeV collected in 2011 with the ATLAS experiment at the Large Hadron Collider. This analysis of the lepton+jets final state is specifically designed for the particular topology that arises from the decay of highly boosted top quarks. The observed t (t) over bar invariant mass spectrum is found to be compatible with the Standard Model prediction and 95% credibility level upper limits are derived on the t (t) over bar production rate through new massive states. An upper limit of 0.7 pb is set on the production cross section times branching fraction of a narrow 1 TeV resonance. A Kaluza-Klein gluon with a mass smaller than 1.5 TeV is excluded.