Measurement of the production cross-section of a single top quark in association with a Zboson in proton–proton collisions at 13TeV with the ATLAS detector
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Elsevier B. V.
Aaboud, M.; Aguilar-Saavedra, Juan Antonio; Atlas Collaboration. Measurement of the production cross-section of a single top quark in association with a Zboson in proton–proton collisions at 13TeV with the ATLAS detector. Physics Letters B 780 (2018) 557–577 [https://doi.org/10.1016/j.physletb.2018.03.023]
SponsorshipWe thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Ar-menia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbai-jan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOSTand NSFC, China; COL-CIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Re-public; 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 Cen-ter, 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 MIZŠ, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallen-berg 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, in-dividual 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, Hori-zon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d’Avenir Labex and Idex, ANR, Région 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. The crucial computing support from all WLCG partners is ac-knowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Swe-den), CC-IN2P3 (France), KIT/GridKA (Germany), INFN–CNAF (Italy), NL-T1(Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2facilities worldwide and large non-WLCG resource providers.
The production of a top quark in association with a Zboson 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 √s=13 TeVare 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, t¯tand Z+jetsproduction. A neural network is used to improve the background rejection and extract the signal. The resulting significance is 4.2σin the data and the expected significance is 5.4σ. The measured cross-section for tZqproduction is 600 ±170 (stat.)±140 (syst.)fb.