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Title: A search for \( t\overline{t} \) resonances using lepton-plus-jets events in proton-proton collisions at \( \sqrt{s}=8 \) TeV with the ATLAS detector

A search for new particles that decay into top quark pairs is reported. The research is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb–1 of proton-proton collision data collected at a centre-A search for new particles that decay into top quark pairs is reported. The search is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb–1 of proton-proton collision data collected at a centre-of-mass energy of √s=8 TeV. The lepton-plus-jets final state is used, where the top pair decays to W+bW-b-bar, with one W boson decaying leptonically and the other hadronically. The invariant mass spectrum of top quark pairs is examined for local excesses or deficits that are inconsistent with the Standard Model predictions. No evidence for a top quark pair resonance is found, and 95% confidence-level limits on the production rate are determined for massive states in benchmark models. The upper limits on the cross-section times branching ratio of a narrow Z' boson decaying to top pairs range from 4.2 pb to 0.03 pb for resonance masses from 0.4 TeV to 3.0 TeV. A narrow leptophobic topcolour Z' boson with mass below 1.8 TeV is excluded.more » Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with Γ/m = 15% decaying to tt-bar. These range from 4.8 pb to 0.03 pb for masses from 0.4 TeV to 3.0 TeV. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.2 TeV.« less
Authors:
 [1]
  1. National Centre for Scientific Research (CNRS), Marseilles (France). Centre for Particle Physics of Marseilles (CPPM); et al.
Publication Date:
Grant/Contract Number:
AC03-76SF00515; AC02-06CH11357; AC02-05CH11231; SC00112704; AC02-98CH10886; AC02-76CH00016; SC0012704; AC03-76SF00098
Type:
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2015; Journal Issue: 8; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Contributing Orgs:
ATLAS Collaboration; The ATLAS collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; exotics; Hadron-Hadron Scattering; top physics
OSTI Identifier:
1222756
Alternate Identifier(s):
OSTI ID: 1222766; OSTI ID: 1223310; OSTI ID: 1223311