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10.1007-JHEP08(2015)148.pdf (1.64 MB)

A search for tt¯ resonances using lepton-plus-jets events in proton-proton collisions at vs = 8 TeV with the ATLAS detector

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posted on 2023-06-09, 05:46 authored by Benedict AllbrookeBenedict Allbrooke, Lily AsquithLily Asquith, Alessandro CerriAlessandro Cerri, C A Chavez Barajas, Antonella De SantoAntonella De Santo, Fabrizio SalvatoreFabrizio Salvatore, I Santoyo Castillo, K Suruliz, Mark SuttonMark Sutton, Iacopo Vivarelli, The ATLAS Collaboration
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 vs=8 TeV. The lepton-plus-jets final state is used, where the top pair decays to W+bW-b¯, 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. Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with G/m = 15% decaying to tt¯. 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.

Funding

ATLAS; G0275; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/I006048/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Journal of High Energy Physics

ISSN

1029-8479

Publisher

Springer Verlag

Issue

8

Volume

2015

Article number

a148

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Experimental Particle Physics Research Group Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-04-11

First Open Access (FOA) Date

2017-04-11

First Compliant Deposit (FCD) Date

2017-04-11

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