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

Detalhes bibliográficos
Autor(a) principal: Onofre, A.
Data de Publicação: 2017
Outros Autores: Castro, Nuno Filipe Silva Fernandes, ATLAS Collaboration
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/1822/48900
Resumo: This 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.
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spelling Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLASCiências Naturais::Ciências FísicasScience & TechnologyThis 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.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; 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 MIZS, 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. 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 (Netherlinfo:eu-repo/semantics/publishedVersionSpringer VerlagUniversidade do MinhoOnofre, A.Castro, Nuno Filipe Silva FernandesATLAS Collaboration20172017-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/1822/48900eng13. Aaboud, 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 = 8 TeV in the lepton + jets channel with ATLAS. [Article]. European Physical Journal C, 77(4). doi: 10.1140/epjc/s10052-017-4819-41434-60441434-605210.1140/epjc/s10052-017-4819-4https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-017-4819-4info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-07-21T12:29:02Zoai:repositorium.sdum.uminho.pt:1822/48900Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:23:56.767470Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
title Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
spellingShingle Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
Onofre, A.
Ciências Naturais::Ciências Físicas
Science & Technology
title_short Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
title_full Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
title_fullStr Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
title_full_unstemmed Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
title_sort Measurement of the W boson polarisation in tt¯ events from pp collisions at s√ = 8 TeV in the lepton + jets channel with ATLAS
author Onofre, A.
author_facet Onofre, A.
Castro, Nuno Filipe Silva Fernandes
ATLAS Collaboration
author_role author
author2 Castro, Nuno Filipe Silva Fernandes
ATLAS Collaboration
author2_role author
author
dc.contributor.none.fl_str_mv Universidade do Minho
dc.contributor.author.fl_str_mv Onofre, A.
Castro, Nuno Filipe Silva Fernandes
ATLAS Collaboration
dc.subject.por.fl_str_mv Ciências Naturais::Ciências Físicas
Science & Technology
topic Ciências Naturais::Ciências Físicas
Science & Technology
description This 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.
publishDate 2017
dc.date.none.fl_str_mv 2017
2017-01-01T00:00:00Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/1822/48900
url http://hdl.handle.net/1822/48900
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 13. Aaboud, 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 = 8 TeV in the lepton + jets channel with ATLAS. [Article]. European Physical Journal C, 77(4). doi: 10.1140/epjc/s10052-017-4819-4
1434-6044
1434-6052
10.1140/epjc/s10052-017-4819-4
https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-017-4819-4
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Springer Verlag
publisher.none.fl_str_mv Springer Verlag
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
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