Measurement of the production cross-section of a single top quark in association with a Z boson in proton-proton collisions at 13 TeV with the ATLAS detector

Abstract

WOS: 000432187800078 ; The production of a top quark in association with a Z boson is investigated. The proton-proton collision data collected by the ATLAS experiment at the LHC in 2015 and 2016 at a centre-of-mass energy of root s = 13 TeV are used, corresponding to an integrated luminosity of 36.1 fb(-1). Events containing three identified leptons (electrons and/or muons) and two jets, one of which is identified as a b-quark jet are selected. The major backgrounds are diboson, tt($)over-bar and Z + jets production. A neural network is used to improve the background rejection and extract the signal. The resulting significance is 4.2 sigma in the data and the expected significance is 5.4 sigma. The measured cross-section for tZq production is 600 +/- 170(stat.)+/- 140(syst.)fb. (C) 2018 The Author(s). Published by Elsevier B.V. ; ANPCyT, ArgentinaANPCyT; YerPhI, Armenia; ARC, AustraliaAustralian Research Council; BMWFW, Austria; FWF, AustriaAustrian Science Fund (FWF); ANAS, AzerbaijanAzerbaijan National Academy of Sciences (ANAS); SSTC, Belarus; CNPq, BrazilNational Council for Scientific and Technological Development (CNPq); FAPESP, BrazilFundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); NSERC, CanadaNatural Sciences and Engineering Research Council of Canada; NRC, Canada; CFI, CanadaCanada Foundation for Innovation; CERN; CONICYT, ChileComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT); CAS, ChinaChinese Academy of Sciences; MOST, ChinaMinistry of Science and Technology, China; NSFC, ChinaNational Natural Science Foundation of China; COLCIENCIAS, ColombiaDepartamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias; MSMT CR, Czech RepublicMinistry of Education, Youth & Sports - Czech RepublicCzech Republic Government; MPO CR, Czech RepublicCzech Republic Government; VSC CR, Czech RepublicCzech Republic Government; DNRF, Denmark; DNSRC, DenmarkDanish Natural Science Research Council; IN2P3-CNRS, FranceCentre National de la Recherche Scientifique (CNRS); CEA-DSM/IRFU, France; SRNSF, Georgia; BMBF, GermanyFederal Ministry of Education & Research (BMBF); HGF, Germany; MPG, GermanyMax Planck Society; GSRT, GreeceGreek Ministry of Development-GSRT; RGC, Hong Kong SAR, ChinaHong Kong Research Grants Council; ISF, IsraelIsrael Science Foundation; I-CORE, Israel; Benoziyo Center, Israel; INFN, ItalyIstituto Nazionale di Fisica Nucleare; MEXT, JapanMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT); JSPS, JapanMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science; CNRST, Morocco; NWO, NetherlandsNetherlands Organization for Scientific Research (NWO)Netherlands Government; RCN, Norway; MNiSW, PolandMinistry of Science and Higher Education, Poland; NCN, Poland; FCT, PortugalPortuguese Foundation for Science and Technology; MNE/IFA, Romania; MES of Russia; NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS, SloveniaSlovenian Research Agency - Slovenia; MIA, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC, Sweden; Wallenberg Foundation, Sweden; SERI, Switzerland; SNSF, SwitzerlandSwiss National Science Foundation (SNSF); Canton of Bern Geneva, Switzerland; MOST, TaiwanMinistry of Science and Technology, Taiwan; TAEK, TurkeyMinistry of Energy & Natural Resources - Turkey; STFC, United KingdomScience & Technology Facilities Council (STFC); DOE, United States of AmericaUnited States Department of Energy (DOE); NSF, United States of AmericaNational Science Foundation (NSF); BCKDF, Canada; Canada Council, Canada; Canarie, Canada; CRC, Canada; Compute Canada, Canada; FQRNT, CanadaFQRNT; Ontario Innovation Trust, Canada; EPLANET, European UnionEuropean Union (EU); ERC, European UnionEuropean Union (EU)European Research Council (ERC); ERDF, European UnionEuropean Union (EU); FP7, European UnionEuropean Union (EU); Horizon, European Union; Investissements d'Avenir Labex, ANR, FranceFrench National Research Agency (ANR); Investissements d'Avenir Idex, ANR,FranceFrench National Research Agency (ANR); Region Auvergne, FranceRegion Auvergne-Rhone-Alpes; Fondation Partager le Savoir, France; DFG, GermanyGerman Research Foundation (DFG); AvH Foundation, GermanyAlexander von Humboldt Foundation; EU-ESFEuropean Union (EU); Greek NSRFGreek Ministry of Development-GSRT; BSF, IsraelUS-Israel Binational Science Foundation; GIF, IsraelGerman-Israeli Foundation for Scientific Research and Development; Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Spain; Generalitat Valenciana, SpainGeneralitat Valenciana; Royal Society, United KingdomRoyal Society of London; Leverhulme Trust, United KingdomLeverhulme Trust; Marie Sklodowska-Curie Actions, European UnionEuropean Union (EU); Canton of Geneva, Switzerland ; We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; SRNSF, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIA, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, Canarie, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, ERDF, FP7, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements d'Avenir Labex and Idex, ANR, Region Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; CERCA Programme Generalitat de Catalunya, Generalitat Valenciana, Spain; the Royal Society and Leverhulme Trust, United Kingdom.