Measurement of τ polarisation in Z/γ ∗ → ττ decays in proton–proton collisions at √ s = 8 TeV with the ATLAS detector Aaboud, M. Aguilar Saavedra, Juan Antonio Atlas Collaboration This paper presents a measurement of the polarisation of τ leptons produced in Z/γ ∗ → ττ decays which i√s 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 ∗ < 116GeVis 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. 2018-04-17T09:54:01Z 2018-04-17T09:54:01Z 2018-02-24 journal article Aaboud, M.; Aguilar-Saavedra, Juan Antonio; Atlas Collaboration. Measurement of τ polarisation in Z/γ ∗ → ττ decays in proton–proton collisions at √ s = 8 TeV with the ATLAS detector. The European Physical Journal C, 78(2): 163 (2018). [http://hdl.handle.net/10481/50284] http://hdl.handle.net/10481/50284 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Springer International Publishing