Measurement of the τ lepton polarization in Z boson decays in proton-proton collisions at (Formula presented.)
Journal of High Energy Physics, vol.2024, no.1, 2024 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 2024 Issue: 1
- Publication Date: 2024
- Doi Number: 10.1007/jhep01(2024)101
- Journal Name: Journal of High Energy Physics
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, INSPEC, zbMATH, Directory of Open Access Journals, Nature Index
- Keywords: Hadron-Hadron Scattering, Tau Physics
- Open Archive Collection: AVESIS Open Access Collection
- Yıldız Technical University Affiliated: No
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 (Formula presented.) 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 Pτ(Z) = −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 = − Pτ(Z) 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 θWeff , independently of the Z boson production mechanism. The obtained value sin2 θWeff = 0.2319 ± 0.0008(stat) ± 0.0018(syst) = 0.2319 ± 0.0019 is in good agreement with measurements at e+ e− colliders. [Figure not available: see fulltext.].