Erlangen 2026 – scientific programme
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T: Fachverband Teilchenphysik
T 68: Standard Model Physics III
T 68.5: Talk
Thursday, March 19, 2026, 17:15–17:30, KH 00.014
Measuring the τ Lepton Polarization in Z → τlep τhad Decays with ATLAS Run 2 Data — •Laman Guliyeva1, Philip Bechtle2, and Christian Grefe2 — 1Bergische Universität Wuppertal, Gaußstr. 20, D-42119 Wuppertal — 2Physikalisches Institut der Universität Bonn, Nußallee 12, D-53115 Bonn
The polarization of leptons produced in Z-boson decays is a key parameter of the electroweak sector, as it provides direct insight into the parity-violating structure of the Zℓℓ coupling. In particular, τ leptons constitute a sensitive probe of electroweak interactions due to their short lifetime and decays occurring within the detector volume. Their hadronic decay modes are especially sensitive to spin-dependent observables, enabling a precise determination of their polarization in Z-boson decays.
This contribution presents a new measurement of the τ-lepton polarization in Z → τlepτhad decays using ATLAS Run-2 data collected in 2018 at √s=13 TeV. This measurement is based on a statistically independent and substantially larger dataset than the Run 1 analysis, making it fully complementary to the previous ATLAS result.
Keywords: ATLAS; tau; polarization; Z boson