Measurement of single top-quark production in association with a W boson in the single-lepton channel at √ s = 8 TeV with the ATLAS detector
We 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, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC and Hong Kong SAR, China; ISF 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; JINR; MESofRussia andNRCKI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZS, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOEandNSF, USA. In addition, individual groups andmembers have received support fromBCKDF, CANARIE, ComputeCanada, CRC and IVADO, Canada; Beijing Municipal Science & Technology Commission, China; COST, ERC, ERDF, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and GIF, Israel; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Goran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in Ref. [78]. ; The production cross-section of a top quark in association with a W boson is measured using proton–proton collisions at √ s = 8 TeV. The dataset corresponds to an integrated luminosity of 20.2 fb−1, and was collected in 2012 by the ATLAS detector at the Large Hadron Collider at CERN. The analysis is performed in the single-lepton channel. Events are selected by requiring one isolated lepton (electron or muon) and at least three jets. A neural network is trained to separate the tW signal from the dominant t ¯t background. The cross-section is extracted from a binned profile maximum-likelihood fit to a two-dimensional discriminant built from the neural-network output and the invariant mass of the hadronically decaying W boson. The measured crosssection is σtW = 26 ± 7 pb, in good agreement with the Standard Model expectation. ; CERN ; ANPCyT ; YerPhI, Armenia ; Australian Research Council ; BMWFW ; Austrian Science Fund (FWF) ; Azerbaijan National Academy of Sciences (ANAS) ; SSTC, Belarus ; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) ; Natural Sciences and Engineering Research Council of Canada (NSERC) Canada Foundation for Innovation ; National Natural Science Foundation of China (NSFC) ; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias ; Ministry of Education, Youth & Sports - Czech Republic ; MPO CR ; Czech Republic Government ; DNRF ; Danish Natural Science Research Council ; Centre National de la Recherche Scientifique (CNRS) CEA-DRF/IRFU, France ; Federal Ministry of Education & Research (BMBF) ; Max Planck Society ; Greek Ministry of Development-GSRT ; RGC and Hong Kong SAR, China ; Israel Science Foundation ; Benoziyo Center, Israel ; Istituto Nazionale di Fisica Nucleare (INFN) ; Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science ; CNRST, Morocco; NWO, Netherlands ; RCN, Norway ; Ministry of Science and Higher Education, Poland NCN, Poland ; Portuguese Foundation for Science and Technology European Commission ; MNE/IFA, Romania ; Russian Federation ; Ministry of Education, Science & Technological Development, Serbia ; MSSR, Slovakia ; Slovenian Research Agency - Slovenia MIZS, Slovenia ; Spanish Government ; SRC ; Wallenberg Foundation, Sweden ; SNSF and Cantons of Bern and Geneva, Switzerland ; Ministry of Science and Technology, Taiwan ; Ministry of Energy & Natural Resources - Turkey ; UK Research & Innovation (UKRI) ; Science & Technology Facilities Council (STFC) ; CANARIE ComputeCanada ; Beijing Municipal Science & Technology Commission ; COST, ERC European Commission Marie Sklodowska-Curie Actions, European Union ; French National Research Agency (ANR) ; German Research Foundation (DFG) ; European Commission ; Alexander von Humboldt Foundation ; Greek NSRF, Greece ; BSF-NSF ; German-Israeli Foundation for Scientific Research and Development ; La Caixa Foundation CERCA Programme Generalitat de Catalunya ; PROMETEO Generalitat Valenciana ; Goran Gustafssons Stiftelse, Sweden ; Royal Society of London ; European Commission ; Leverhulme Trust ; NDGF (Denmark, Norway, Sweden) ; KIT/GridKA (Germany) ; INFN-CNAF (Italy) ; NL-T1 (Netherlands), PIC (Spain) ; ASGC (Taiwan) ; BNL (USA)