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


Aad, G ORCID: 0000-0002-6665-4934, Abbott, B ORCID: 0000-0002-5888-2734, Abbott, DC ORCID: 0000-0002-7248-3203, Abeling, K ORCID: 0000-0002-1002-1652, Abidi, SH ORCID: 0000-0002-8496-9294, Aboulhorma, A ORCID: 0000-0002-9987-2292, Abramowicz, H ORCID: 0000-0001-5329-6640, Abreu, H ORCID: 0000-0002-1599-2896, Abulaiti, Y ORCID: 0000-0003-0403-3697, Abusleme Hoffman, AC ORCID: 0000-0003-0762-7204 et al (show 2926 more authors) (2023) Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at √s = 13TeV with the ATLAS experiment. Physics Letters B, 843. p. 137829.

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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.

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 27 Jun 2023 16:25
Last Modified: 09 Apr 2024 16:15
DOI: 10.1016/j.physletb.2023.137829
Open Access URL: https://www.sciencedirect.com/science/article/pii/...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3171330
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