Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment

The ATLAS collaboration

doi:10.1016/j.physletb.2023.137829

Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment

The ATLAS collaboration

Radiation Imaging and Advanced Diagnosti

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6 Scopus citations

Abstract

A measurement of the polarisation of W bosons produced in top-quark decays is presented, using proton–proton collision data at a centre-of-mass energy of s=13 TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb⁻¹. The measurement is performed selecting tt¯ events decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cos⁡θ^⁎ variable, where θ^⁎ is the angle between the momentum direction of the charged lepton from the W boson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the W boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cos⁡θ^⁎ angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f₀=0.684±0.005(stat.)±0.014(syst.), f_L=0.318±0.003(stat.)±0.008(syst.) and f_R=−0.002±0.002(stat.)±0.014(syst.), in agreement with the Standard Model prediction.

Original language	English
Article number	137829
Journal	Physics Letters B
Volume	843
DOIs	https://doi.org/10.1016/j.physletb.2023.137829
State	Published - Aug 10 2023

Funding

We acknowledge the support of ANPCyT , Argentina; YerPhI , Armenia; ARC , Australia; BMWFW and FWF , Austria; ANAS , Azerbaijan; CNPq and FAPESP , Brazil; NSERC , NRC and CFI , Canada; CERN ; ANID , Chile; CAS , MOST and NSFC , China; Minciencias , Colombia; MEYS CR, Czech Republic; DNRF and DNSRC , Denmark; IN2P3-CNRS and CEA-DRF/IRFU , France; SRNSFG , Georgia; BMBF , HGF and MPG , Germany; GSRI , Greece; RGC and Hong Kong SAR , China; ISF and Benoziyo Center , Israel; INFN , Italy; MEXT and JSPS , Japan; CNRST , Morocco; NWO , Netherlands; RCN , Norway; MEiN , Poland; FCT , Portugal; MNE/IFA , Romania; MESTD , Serbia; MSSR , Slovakia; ARRS and MIZŠ , Slovenia; DSI/NRF , South Africa; MICINN , Spain; SRC and Wallenberg Foundation , Sweden; SERI , SNSF and Cantons of Bern and Geneva , Switzerland; MOST , Taiwan; TENMAK , Türkiye; STFC , United Kingdom; DOE and NSF , United States of America. In addition, individual groups and members have received support from BCKDF , Canarie , Compute Canada and CRC , Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST , ERC , ERDF , Horizon 2020 and Marie Skłodowska-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 MINERVA , Israel; Norwegian Financial Mechanism 2014-2021, Norway; NCN and NAWA , Poland; La Caixa Banking Foundation , CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana , Spain; Göran Gustafssons Stiftelser , Sweden; The Royal Society and Leverhulme Trust , United Kingdom. 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; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TENMAK, Türkiye; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, Canarie, Compute Canada and CRC, Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-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 MINERVA, Israel; Norwegian Financial Mechanism 2014-2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelser, 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. [1].

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10.1016/j.physletb.2023.137829

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@article{9e0e2807fb4247c2a0aa51e3ed6b6e0f,

title = "Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment",

abstract = "A measurement of the polarisation of W bosons produced in top-quark decays is presented, using proton–proton collision data at a centre-of-mass energy of s=13 TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb−1. The measurement is performed selecting tt¯ events decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cos⁡θ⁎ variable, where θ⁎ is the angle between the momentum direction of the charged lepton from the W boson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the W boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cos⁡θ⁎ angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f0=0.684±0.005(stat.)±0.014(syst.), fL=0.318±0.003(stat.)±0.008(syst.) and fR=−0.002±0.002(stat.)±0.014(syst.), in agreement with the Standard Model prediction.",

author = "{The ATLAS collaboration} and G. Aad and B. Abbott and Abbott, {D. C.} and K. Abeling and Abidi, {S. H.} and A. Aboulhorma and H. Abramowicz and H. Abreu and Y. Abulaiti and {Abusleme Hoffman}, {A. C.} and Acharya, {B. S.} and {Adam Bourdarios}, C. and L. Adamczyk and L. Adamek and Addepalli, {S. V.} and J. Adelman and A. Adiguzel and S. Adorni and T. Adye and Affolder, {A. A.} and Y. Afik and Agaras, {M. N.} and J. Agarwala and A. Aggarwal and C. Agheorghiesei and Aguilar-Saavedra, {J. A.} and A. Ahmad and F. Ahmadov and Ahmed, {W. S.} and S. Ahuja and X. Ai and G. Aielli and {Ait Tamlihat}, M. and B. Aitbenchikh and I. Aizenberg and M. Akbiyik and {\AA}kesson, {T. P.A.} and Akimov, {A. V.} and {Al Khoury}, K. and Alberghi, {G. L.} and J. Albert and P. Albicocco and S. Alderweireldt and M. Aleksa and Aleksandrov, {I. N.} and C. Alexa and T. Alexopoulos and A. Alfonsi and F. Alfonsi and Steinhebel, {A. L.}",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = aug,

day = "10",

doi = "10.1016/j.physletb.2023.137829",

language = "English",

volume = "843",

journal = "Physics Letters B",

issn = "0370-2693",

publisher = "Elsevier",

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TY - JOUR

T1 - Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment

AU - The ATLAS collaboration

AU - Aad, G.

AU - Abbott, B.

AU - Abbott, D. C.

AU - Abeling, K.

AU - Abidi, S. H.

AU - Aboulhorma, A.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abulaiti, Y.

AU - Abusleme Hoffman, A. C.

AU - Acharya, B. S.

AU - Adam Bourdarios, C.

AU - Adamczyk, L.

AU - Adamek, L.

AU - Addepalli, S. V.

AU - Adelman, J.

AU - Adiguzel, A.

AU - Adorni, S.

AU - Adye, T.

AU - Affolder, A. A.

AU - Afik, Y.

AU - Agaras, M. N.

AU - Agarwala, J.

AU - Aggarwal, A.

AU - Agheorghiesei, C.

AU - Aguilar-Saavedra, J. A.

AU - Ahmad, A.

AU - Ahmadov, F.

AU - Ahmed, W. S.

AU - Ahuja, S.

AU - Ai, X.

AU - Aielli, G.

AU - Ait Tamlihat, M.

AU - Aitbenchikh, B.

AU - Aizenberg, I.

AU - Akbiyik, M.

AU - Åkesson, T. P.A.

AU - Akimov, A. V.

AU - Al Khoury, K.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Albicocco, P.

AU - Alderweireldt, S.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexa, C.

AU - Alexopoulos, T.

AU - Alfonsi, A.

AU - Alfonsi, F.

AU - Steinhebel, A. L.

PY - 2023/8/10

Y1 - 2023/8/10

N2 - A measurement of the polarisation of W bosons produced in top-quark decays is presented, using proton–proton collision data at a centre-of-mass energy of s=13 TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb−1. The measurement is performed selecting tt¯ events decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cos⁡θ⁎ variable, where θ⁎ is the angle between the momentum direction of the charged lepton from the W boson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the W boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cos⁡θ⁎ angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f0=0.684±0.005(stat.)±0.014(syst.), fL=0.318±0.003(stat.)±0.008(syst.) and fR=−0.002±0.002(stat.)±0.014(syst.), in agreement with the Standard Model prediction.

AB - A measurement of the polarisation of W bosons produced in top-quark decays is presented, using proton–proton collision data at a centre-of-mass energy of s=13 TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb−1. The measurement is performed selecting tt¯ events decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cos⁡θ⁎ variable, where θ⁎ is the angle between the momentum direction of the charged lepton from the W boson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the W boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cos⁡θ⁎ angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f0=0.684±0.005(stat.)±0.014(syst.), fL=0.318±0.003(stat.)±0.008(syst.) and fR=−0.002±0.002(stat.)±0.014(syst.), in agreement with the Standard Model prediction.

UR - http://www.scopus.com/inward/record.url?scp=85165885818&partnerID=8YFLogxK

U2 - 10.1016/j.physletb.2023.137829

DO - 10.1016/j.physletb.2023.137829

M3 - Article

AN - SCOPUS:85165885818

SN - 0370-2693

VL - 843

JO - Physics Letters B

JF - Physics Letters B

M1 - 137829

ER -

Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment

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