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

Aaboud, M, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H
et al (show 2840 more authors) (2017) Measurement of the <i>W</i> boson polarisation in <i>t</i>(<i>t</i>)over-barevents from <i>pp</i> collisions at √<i>s</i>=8 TeV in the lepton plus jets channel with ATLAS. EUROPEAN PHYSICAL JOURNAL C, 77 (4). 264-.

[img] Text
1612.02577v2.pdf - Published version

Download (1MB)


This paper presents a measurement of the polarisation of <i>W</i> bosons from [Formula: see text] decays, reconstructed in events with one high-[Formula: see text] lepton and at least four jets. Data from <i>pp</i> collisions at the LHC were collected at [Formula: see text] = 8 TeV and correspond to an integrated luminosity of 20.2 fb[Formula: see text]. The angle [Formula: see text] between the <i>b</i>-quark from the top quark decay and a direct <i>W</i> boson decay product in the <i>W</i> boson rest frame is sensitive to the <i>W</i> boson polarisation. Two different <i>W</i> decay products are used as polarisation analysers: the charged lepton and the down-type quark for the leptonically and hadronically decaying <i>W</i> boson, respectively. The most precise measurement of the <i>W</i> boson polarisation via the distribution of [Formula: see text] is obtained using the leptonic analyser and events in which at least two of the jets are tagged as <i>b</i>-quark jets. The fitted fractions of longitudinal, left- and right-handed polarisation states are [Formula: see text], [Formula: see text] and [Formula: see text], and are the most precisely measured <i>W</i> boson polarisation fractions to date. Limits on anomalous couplings of the <i>Wtb</i> vertex are set.

Item Type: Article
Additional Information: 42 pages in total, author list starting page 26, 6 figures, 5 tables, published in EPJC. All figures including auxiliary figures are available at v3 includes modifications described in the erratum that can be found at
Uncontrolled Keywords: ATLAS Collaboration
Depositing User: Symplectic Admin
Date Deposited: 15 Jun 2017 10:34
Last Modified: 12 Oct 2023 17:54
DOI: 10.1140/epjc/s10052-017-4819-4
Related URLs: