Measurement of τ polarisation in Ζ/γ* → ττ decays in proton–proton collisions at √s = 8 TeV with the ATLAS detector
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Date
2018
Authors
Aaboud, M.
Aad, G.
Abbott, B.
Abdinov, O.
Abeloos, B.
Abidi, S.
AbouZeid, O.
Abraham, N.
Abramowicz, H.
Abreu, H.
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Journal article
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European Physical Journal C, 2018; 78(2):163-1-163-30
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M. Aaboud ... D. Duvnjak ... P. Jackson ... L. Lee ... A. Petridis ... M.J. White ... [et al.] (The ATLAS Collaboration)
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Abstract
This paper presents a measurement of the polarisation of τ leptons produced in Z/γ* → ττ decays which is performed with a dataset of proton-proton collisions at √s = 8 TeV, corresponding to an integrated luminosity of 20.2 fb⁻¹ recorded with the ATLAS detector at the LHC in 2012. The Z/γ* → ττ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z/γ* mass range of 66 < mZ/γ* < 116 GeV is found to be Pτ = −0.14±0.02(stat)±0.04(syst). It is in agreement with the Standard Model prediction of Pτ = −0.1517 ± 0.0019, which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.
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© CERN for the benefit of the ATLAS collaboration 2018. This article is an open access publication. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecomm ons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Funded by SCOAP3.