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

G. Aad; B Abbott; J. Abdallah; O Abdinov; B Abeloos; Torsten Åkesson; Simona Bocchetta; LENE BRYNGEMARK; Caterina Doglioni; Vincent Hedberg; Göran Jarlskog; Else Lytken; Ulf Mjörnmark; Oxana Smirnova; Oleksandr Viazlo; ATLAS Collaboration

doi:10.1140/epjc/s10052-017-4819-4

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

G. Aad, B Abbott, J. Abdallah, O Abdinov, B Abeloos, Torsten Åkesson, Simona Bocchetta, LENE BRYNGEMARK, Caterina Doglioni, Vincent Hedberg, Göran Jarlskog, Else Lytken, Ulf Mjörnmark, Oxana Smirnova, Oleksandr Viazlo, ATLAS Collaboration

Research output: Contribution to journal › Article › peer-review

Abstract

This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT 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 cos θ∗ 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. © 2017, CERN for the benefit of the ATLAS collaboration.

Original language	English
Article number	264
Journal	European Physical Journal C
Volume	77
Issue number	4
DOIs	https://doi.org/10.1140/epjc/s10052-017-4819-4
Publication status	Published - 2017

Bibliographical note

Export Date: 12 June 2017

Subject classification (UKÄ)

Subatomic Physics

Access to Document

10.1140/epjc/s10052-017-4819-4

Cite this

Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., Åkesson, T., Bocchetta, S., BRYNGEMARK, LENE., Doglioni, C., Hedberg, V., Jarlskog, G., Lytken, E., Mjörnmark, U., Smirnova, O., Viazlo, O., & ATLAS Collaboration (2017). Measurement of the W boson polarisation in tt¯ events from pp collisions at √s = 8 TeV in the lepton + jets channel with ATLAS. European Physical Journal C, 77(4), Article 264. https://doi.org/10.1140/epjc/s10052-017-4819-4

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

abstract = "This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT 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 cos θ∗ 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. {\textcopyright} 2017, CERN for the benefit of the ATLAS collaboration.",

author = "M Aaboud and G. Aad and B Abbott and J. Abdallah and O Abdinov and B Abeloos and Torsten {\AA}kesson and Simona Bocchetta and LENE BRYNGEMARK and Caterina Doglioni and Vincent Hedberg and G{\"o}ran Jarlskog and Else Lytken and Ulf Mj{\"o}rnmark and Oxana Smirnova and Oleksandr Viazlo and {ATLAS Collaboration}",

note = "Export Date: 12 June 2017",

year = "2017",

doi = "10.1140/epjc/s10052-017-4819-4",

language = "English",

volume = "77",

journal = "European Physical Journal C",

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Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, Åkesson, T, Bocchetta, S, BRYNGEMARK, LENE , Doglioni, C , Hedberg, V , Jarlskog, G , Lytken, E, Mjörnmark, U, Smirnova, O, Viazlo, O & ATLAS Collaboration 2017, 'Measurement of the W boson polarisation in tt¯ events from pp collisions at √s = 8 TeV in the lepton + jets channel with ATLAS', European Physical Journal C, vol. 77, no. 4, 264. https://doi.org/10.1140/epjc/s10052-017-4819-4

TY - JOUR

T1 - Measurement of the W boson polarisation in tt¯ events from pp collisions at √s = 8 TeV in the lepton + jets channel with ATLAS

AU - Aaboud, M

AU - Aad, G.

AU - Abbott, B

AU - Abdallah, J.

AU - Abdinov, O

AU - Abeloos, B

AU - Åkesson, Torsten

AU - Bocchetta, Simona

AU - BRYNGEMARK, LENE

AU - Doglioni, Caterina

AU - Hedberg, Vincent

AU - Jarlskog, Göran

AU - Lytken, Else

AU - Mjörnmark, Ulf

AU - Smirnova, Oxana

AU - Viazlo, Oleksandr

AU - ATLAS Collaboration

N1 - Export Date: 12 June 2017

PY - 2017

Y1 - 2017

N2 - This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT 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 cos θ∗ 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. © 2017, CERN for the benefit of the ATLAS collaboration.

AB - This paper presents a measurement of the polarisation of W bosons from tt¯ decays, reconstructed in events with one high-pT 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 cos θ∗ 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. © 2017, CERN for the benefit of the ATLAS collaboration.

U2 - 10.1140/epjc/s10052-017-4819-4

DO - 10.1140/epjc/s10052-017-4819-4

M3 - Article

C2 - 28515670

SN - 1434-6044

VL - 77

JO - European Physical Journal C

JF - European Physical Journal C

IS - 4

M1 - 264