Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS

M. Aaboud; G. Aad; B. Abbott; J. Abdallah; O. Abdinov; B Abeloos; O.S. AbouZeid; NL Abraham; H. Abramowicz; H. Abreu; R. Abreu; Y. Abulaiti; B.S. Acharya; S. Adachi; L. Adamczyk; David L. Adams; J P Adelman; T. Adye; Mogens Dam; Jørn Dines Hansen; Jørgen Beck Hansen; Stefania Xella; Peter Henrik Hansen; Troels Christian Petersen; Ask Emil Løvschall-Jensen; Alejandro Alonso Diaz; James William Monk; Lars Egholm Pedersen; Graig Wiglesworth; Gorm Aske Gram Krohn Galster; Simon Holm Stark; Geert-Jan Besjes; Fabian Alexander Jürgen Thiele; Flavia de Almeida Dias; Milena Bajic

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

Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS

M. Aaboud, G. Aad, B. Abbott, J. Abdallah, O. Abdinov, B Abeloos, O.S. AbouZeid, NL Abraham, H. Abramowicz, H. Abreu, R. Abreu, Y. Abulaiti, B.S. Acharya, S. Adachi, L. Adamczyk, David L. Adams, J P Adelman, T. Adye, Mogens Dam, Jørn Dines HansenJørgen Beck Hansen, Stefania Xella, Peter Henrik Hansen, Troels Christian Petersen, Ask Emil Løvschall-Jensen, Alejandro Alonso Diaz, James William Monk, Lars Egholm Pedersen, Graig Wiglesworth, Gorm Aske Gram Krohn Galster, Simon Holm Stark, Geert-Jan Besjes, Fabian Alexander Jürgen Thiele, Flavia de Almeida Dias, Milena Bajic

Experimental Particle Physics

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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.

Original language	English
Article number	264
Journal	European Physical Journal C
Volume	77
Issue number	4
ISSN	1434-6044
DOIs	https://doi.org/10.1140/epjc/s10052-017-4819-4
Publication status	Published - 1 Apr 2017

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Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., AbouZeid, O. S., Abraham, NL., Abramowicz, H., Abreu, H., Abreu, R., Abulaiti, Y., Acharya, B. S., Adachi, S., Adamczyk, L., Adams, D. L., Adelman, J. P., Adye, T., Dam, M., ... Bajic, M. (2017). Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS. European Physical Journal C, 77(4), Article 264. https://doi.org/10.1140/epjc/s10052-017-4819-4

Aaboud, M, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adachi, S, Adamczyk, L, Adams, DL, Adelman, JP, Adye, T, Dam, M , Hansen, JD , Hansen, JB , Xella, S , Hansen, PH , Petersen, TC, Løvschall-Jensen, AE, Alonso Diaz, A, Monk, JW, Pedersen, LE, Wiglesworth, G, Galster, GAGK, Stark, SH, Besjes, G-J, Thiele, FAJ, de Almeida Dias, F & Bajic, M 2017, 'Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS', European Physical Journal C, vol. 77, no. 4, 264. https://doi.org/10.1140/epjc/s10052-017-4819-4

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title = "Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus 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.",

author = "M. Aaboud and G. Aad and B. Abbott and J. Abdallah and O. Abdinov and B Abeloos and O.S. AbouZeid and NL Abraham and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and B.S. Acharya and S. Adachi and L. Adamczyk and Adams, {David L.} and Adelman, {J P} and T. Adye and Mogens Dam and Hansen, {J{\o}rn Dines} and Hansen, {J{\o}rgen Beck} and Stefania Xella and Hansen, {Peter Henrik} and Petersen, {Troels Christian} and L{\o}vschall-Jensen, {Ask Emil} and {Alonso Diaz}, Alejandro and Monk, {James William} and Pedersen, {Lars Egholm} and Graig Wiglesworth and Galster, {Gorm Aske Gram Krohn} and Stark, {Simon Holm} and Geert-Jan Besjes and Thiele, {Fabian Alexander J{\"u}rgen} and {de Almeida Dias}, Flavia and Milena Bajic",

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

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TY - JOUR

T1 - Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS

AU - Aaboud, M.

AU - Aad, G.

AU - Abbott, B.

AU - Abdallah, J.

AU - Abdinov, O.

AU - Abeloos, B

AU - AbouZeid, O.S.

AU - Abraham, NL

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Abulaiti, Y.

AU - Acharya, B.S.

AU - Adachi, S.

AU - Adamczyk, L.

AU - Adams, David L.

AU - Adelman, J P

AU - Adye, T.

AU - Dam, Mogens

AU - Hansen, Jørn Dines

AU - Hansen, Jørgen Beck

AU - Xella, Stefania

AU - Hansen, Peter Henrik

AU - Petersen, Troels Christian

AU - Løvschall-Jensen, Ask Emil

AU - Alonso Diaz, Alejandro

AU - Monk, James William

AU - Pedersen, Lars Egholm

AU - Wiglesworth, Graig

AU - Galster, Gorm Aske Gram Krohn

AU - Stark, Simon Holm

AU - Besjes, Geert-Jan

AU - Thiele, Fabian Alexander Jürgen

AU - de Almeida Dias, Flavia

AU - Bajic, Milena

PY - 2017/4/1

Y1 - 2017/4/1

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.

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.

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

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

M3 - Journal article

SN - 1434-6044

VL - 77

JO - European Physical Journal C

JF - European Physical Journal C

IS - 4

M1 - 264

ER -

Measurement of the W boson polarisation in t(t)over-barevents from pp collisions at root s=8 TeV in the lepton plus jets channel with ATLAS

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