Allbrooke, B M M, Asquith, L, Cerri, A, Chavez Barajas, C A, De Santo, A, Salvatore, F, Santoyo Castillo, I, Suruliz, K, Sutton, M R, Vivarelli, I and The ATLAS Collaboration, (2018) Measurement of τ polarisation in Z/γ∗ → ττ decays in proton–proton collisions at √s = 8 TeV with the ATLAS detector. European Physical Journal C, 78 (163). ISSN 1434-6044

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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∗ < 116GeV 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.

Item Type:	Article
Schools and Departments:	School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups:	Experimental Particle Physics Research Group
Subjects:	Q Science > QC Physics
Depositing User:	Billy Wichaidit
Date Deposited:	25 May 2018 08:45
Last Modified:	06 Jun 2018 13:43
URI:	http://sro.sussex.ac.uk/id/eprint/76110

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