학술논문
Measurement of the τ lepton polarization in Z boson decays in proton-proton collisions at s = 13 TeV
Document Type
Original Paper
Author
Source
Journal of High Energy Physics. 2024(1)
Subject
Language
English
ISSN
1029-8479
Abstract
Abstract: The polarization of τ leptons is measured using leptonic and hadronic τ lepton decays in Z → τ+ τ− events in proton-proton collisions at sPτZ−PτZθWeffθWeff = 13 TeV recorded by CMS at the CERN LHC with an integrated luminosity of 36.3 fb−1 . The measured τ− lepton polarization at the Z boson mass pole is sPτZ−PτZθWeffθWeff = −0.144 ± 0.006 (stat) ± 0.014 (syst) = −0.144 ± 0.015, in good agreement with the measurement of the τ lepton asymmetry parameter of Aτ = 0.1439 ± 0.0043 = sPτZ−PτZθWeffθWeff at LEP. The τ lepton polarization depends on the ratio of the vector to axial-vector couplings of the τ leptons in the neutral current expression, and thus on the effective weak mixing angle sin2 sPτZ−PτZθWeffθWeff, independently of the Z boson production mechanism. The obtained value sin2 sPτZ−PτZθWeffθWeff = 0.2319 ± 0.0008(stat) ± 0.0018(syst) = 0.2319 ± 0.0019 is in good agreement with measurements at e+ e− colliders.