Measurement of the W boson polarisation in tt¯ events from pp collisions at √s=8TeV in the lepton + jets channel with ATLAS

dc.contributor.authorAaboud, M.
dc.contributor.authorAlbert, Justin
dc.contributor.authorElliot, Alison A.
dc.contributor.authorFincke-Keeler, J.
dc.contributor.authorHamano, Kenji
dc.contributor.authorHill, Ewan Chin
dc.contributor.authorKeeler, Richard
dc.contributor.authorKowalewski, Robert
dc.contributor.authorKuwertz, E. S.
dc.contributor.authorKwan, Tony
dc.contributor.authorLeBlanc, Matthew Edgar
dc.contributor.authorLefebvre, Michel
dc.contributor.authorMcPherson, Robert A.
dc.contributor.authorPearce, James D.
dc.contributor.authorSeuster, Rolf
dc.contributor.authorSobie, Randall J.
dc.contributor.authorTrovatelli, M.
dc.contributor.authorVenturi, M.
dc.contributor.authorATLAS Collaboration
dc.date.accessioned2020-02-14T00:48:56Z
dc.date.available2020-02-14T00:48:56Z
dc.date.copyright2017en_US
dc.date.issued2017
dc.description.abstractThis paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-p T lepton and at least four jets. Data from pp collisions at the LHC were collected at s√ = 8 TeV and correspond to an integrated luminosity of 20.2 fb−1. The angle θ∗ between the b-quark from the top quark decay and a direct W boson decay product in the W boson rest frame is sensitive to the W boson polarisation. Two different W decay products are used as polarisation analysers: the charged lepton and the down-type quark for the leptonically and hadronically decaying W boson, respectively. The most precise measurement of the W boson polarisation via the distribution of cosθ∗ is obtained using the leptonic analyser and events in which at least two of the jets are tagged as b-quark jets. The fitted fractions of longitudinal, left- and right-handed polarisation states are F0= 0.709 ± 0.019, FL= 0.299 ± 0.015 and FR= −0.008 ± 0.014, and are the most precisely measured W boson polarisation fractions to date. Limits on anomalous couplings of the Wtb vertex are set.en_US
dc.description.reviewstatusRevieweden_US
dc.description.scholarlevelFacultyen_US
dc.description.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, 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 MIZŠ, 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 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 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. [82].en_US
dc.identifier.citationAaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; … & Zwalinski, L. (2017). Measurement of the W boson polarisation in tt¯ events from pp collisions at √s=8TeV in the lepton + jets channel with ATLAS. The European Physical Journal C, 77(4), article 264. DOI: 10.1140/epjc/s10052-017-4819-4en_US
dc.identifier.urihttps://doi.org/10.1140/epjc/s10052-017-4819-4
dc.identifier.urihttp://hdl.handle.net/1828/11549
dc.language.isoenen_US
dc.publisherThe European Physical Journal Cen_US
dc.subject.departmentDepartment of Physics and Astronomy
dc.titleMeasurement of the W boson polarisation in tt¯ events from pp collisions at √s=8TeV in the lepton + jets channel with ATLASen_US
dc.typeArticleen_US

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