A search for tt¯ resonances using lepton-plus-jets events in proton-proton collisions at s√=8 TeV with the ATLAS detector
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ExoticsHadron-Hadron scatteringTop physics
Aad, G., Abbott, B., Abdallah, J. et al. A search for tt¯ resonances using lepton-plus-jets events in proton-proton collisions at s√=8 TeV with the ATLAS detector. J. High Energ. Phys. 2015, 148 (2015). [https://doi.org/10.1007/JHEP08(2015)148]
SponsorshipANPCyT; YerPhI, Armenia; Australian Research Council; BMWFW, Austria; Azerbaijan National Academy of Sciences (ANAS); SSTC, Belarus; National Council for Scientific and Technological Development (CNPq); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Natural Sciences and Engineering Research Council of Canada; NRC, Canada; Canada Foundation for Innovation; CERN; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT); Chinese Academy of Sciences; Ministry of Science and Technology, China; National Natural Science Foundation of China; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias; Ministry of Education, Youth & Sports - Czech Republic Czech Republic Government; DNRF, Denmark; Danish Natural Science Research Council; Lundbeckfonden; EPLANET; European Research Council (ERC); NSRF; European Union (EU); Centre National de la Recherche Scientifique (CNRS); CEA-DSM/IRFU, France; GNSF, Georgia; Federal Ministry of Education & Research (BMBF); German Research Foundation (DFG); HGF, Germany; Max Planck Society; Alexander von Humboldt Foundation; Greek Ministry of Development-GSRT; NSRF, Greece; RGC, China; Hong Kong SAR, China; Israel Science Foundation; MINERVA, Israel; German-Israeli Foundation for Scientific Research and Development; I-CORE, Israel; Benoziyo Center, Israel; Istituto Nazionale di Fisica Nucleare (INFN); Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science; CNRST, Morocco; FOM (The Netherlands) Netherlands Government; Netherlands Organization for Scientific Research (NWO) Netherlands Government; BRF, Norway; RCN, Norway; Ministry of Science and Higher Education, Poland; NCN, Poland; GRICES, Portugal; Portuguese Foundation for Science and Technology; MNE/IFA, Romania; Russian Federation; NRC KI, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; Slovenian Research Agency - Slovenia; MIZ. S, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC, Sweden; Wallenberg Foundation, Sweden; SER, Switzerland; Swiss National Science Foundation (SNSF); Cantons of Bern and Geneva, Switzerland; National Science Council of Taiwan; Ministry of Energy & Natural Resources - Turkey; Royal Society and Leverhulme Trust, United Kingdom; United States Department of Energy (DOE); National Science Foundation (NSF); Science & Technology Facilities Council (STFC) ST/H00100X/1 ST/K001302/1 ST/I00372X/1 GRIDPP ST/L003325/1 PP/E000355/1 ST/I005803/1 GRIDPP ST/K001264/1 ATLAS 1366364 ST/L001179/1 ST/K001310/1 ATLAS Upgrades ST/K001248/1 ST/J004928/1 ST/K001310/1 ATLAS ST/M000761/1 ST/L000970/1 ATLAS Upgrade ST/K001426/1 ATLAS ST/K00073X/1 ST/J004928/1 ATLAS Upgrades 1521422 ST/K003658/1 ST/K00140X/1 ST/K001329/1 ST/K001310/1 ST/H00100X/2 1082012 ST/K003658/1 GRIDPP ST/J004944/1 ST/I006056/1 ATLAS Upgrade ATLAS ST/M503575/1 ST/M001431/1 ST/L006480/1 ST/J005487/1 ST/I006056/1 ST/I000186/1 ST/M002071/1 ATLAS Upgrades ST/M001733/1 ST/L001179/1 ATLAS Upgrade ST/K001396/1 ATLAS ST/J501074/1 ST/I00372X/1 ST/J00474X/1 ATLAS Upgrades ST/K000705/1 ST/I006080/1 1334588 GRIDPP PP/E000347/1 ST/L001179/1 ATLAS Upgrades ST/M007103/1 ATLAS Upgrades ST/N000463/1 ST/M001504/1 ST/M001474/1 ST/K001418/1 ST/K001388/1 ST/J005525/1 ST/L001209/1 ATLAS Upgrades ST/L00352X/1 ST/N000307/1 ST/J005576/1 ST/H001093/1 ST/M004821/1 GRIDPP ST/L001195/1 ST/I006056/1 ATLAS Upgrades ST/G50228X/1 1201187 ST/G502320/1 PP/E003087/1 ST/K001361/1 ATLAS Upgrades ST/K00137X/1 ST/L003414/1 ST/M006980/1 ST/M002306/1 ATLAS Upgrades ST/K001361/1 ST/H001093/2 ST/K001310/1 LHCb ST/L003112/1 ST/M006980/1 ATLAS Upgrades ST/J004928/1 ATLAS Upgrade PP/E000444/1 ST/M001407/1 ST/M000664/1 ST/K001361/1 LHCb ST/K001361/1 ATLAS ST/J00474X/1 ST/I005803/1 ST/I000178/1 1366825 ST/L001144/1 ST/L000970/1 ATLAS Upgrades ST/K50208X/1 ST/K001310/1 LHCb Upgrades ST/L000970/1 PP/E002846/1 PP/D002915/1 1575161 ST/K001361/1 LHCb Upgrades ST/K001361/1 MINOS/MINOS+ ST/M002306/1 ST/M003213/1 ST/M004821/1; ICREA
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¯¯, 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 Γ/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.