Measurement of $\tau$ polarization in $W -> \tau \nu$ decays with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

In this paper, a measurement of tau polarization in W->taunu decays is presented. It is measured from the energies of the decay products in hadronic tau decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb^-1, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the tau polarization is Ptau = -1.06 +/- 0.04 (stat) + 0.05 (syst) - 0.07 (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95% CL interval [-1,-0.91]. Measurements of tau polarization have not previously been made at hadron colliders.

Note:

10 pages plus author list (25 pages total), 4 figures, 4 tables, revised author list, matches published EPJC version

tau: polarization: measured
tau: semileptonic decay
p p: scattering
W: leptonic decay
ATLAS
charged particle: final state
rho(770): intermediate state
transverse energy: missing-energy
charge: asymmetry
experimental results

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