Aaboud, M;
Aad, G;
Abbott, B;
Abdallah, J;
Abdinov, O;
Abeloos, B;
AbouZeid, OS;
... Zwalinski, L; + view all
(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.
The European Physical Journal C
, 77
(4)
, Article 264. 10.1140/epjc/s10052-017-4819-4.
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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.
| Type: | Article |
|---|---|
| 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 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1140/epjc/s10052-017-4819-4 |
| Publisher version: | http://doi.org/10.1140/epjc/s10052-017-4819-4 |
| Language: | English |
| Additional information: | © CERN for the benefit of the ATLAS collaboration 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. |
| Keywords: | Science & Technology, Physical Sciences, Physics, Particles & Fields, Physics, TOP-QUARK PRODUCTION, PARTON DISTRIBUTIONS, HADRON COLLIDERS, PAIR PRODUCTION, RESUMMATION, LHC |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1532417 |
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