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Oxana Smirnova

Oxana Smirnova

Senior Lecturer, Deputy Head of division

Oxana Smirnova

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


  • G. Aad
  • T.P.A. Åkesson
  • E.E. Corrigan
  • C. Doglioni
  • P.A. Ekman
  • J. Geisen
  • V. Hedberg
  • H. Herde
  • G. Jarlskog
  • B. Konya
  • E. Lytken
  • J.U. Mjörnmark
  • R. Poettgen
  • N.D. Simpson
  • E. Skorda
  • O. Smirnova
  • L. Zwalinski

Summary, in English

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. © 2023 The Author(s)


  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year





Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics



Document type

Journal article




  • Subatomic Physics




  • ISSN: 0370-2693