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

ATLAS Publications, T.M. Carter, R.Y. Gonzalez Andana, A. Hasib, M.P. Heath, V.A. Parrish, E.A. Pender, E.P. Takeva, N. Themistokleous, E.M. Villhauer, E. Zaid

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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 t¯t 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.
Original languageEnglish
Article number137829
Pages (from-to)1-22
Number of pages22
JournalPhysics Letters B
Volume843
DOIs
Publication statusPublished - 10 Aug 2023

Fingerprint

Dive into the research topics of 'Measurement of the polarisation of W bosons produced in top-quark decays using dilepton events at s=13 TeV with the ATLAS experiment'. Together they form a unique fingerprint.

Cite this