In this paper, a measurement of tau polarization in W -> tau nu 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 P-tau = -1.06 +/- 0.04 (stat)(-0.07)(+0.05) (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. RI Fazio, Salvatore /G-5156-2010; Fabbri, Laura/H-3442-2012; Villa, Mauro/C-9883-2009; Jones, Roger/H-5578-2011; valente, paolo/A-6640-2010; Takai, Helio/C-3301-2012; Delmastro, Marco/I-5599-2012; Livan, Michele/D-7531-2012

Measurement of tau polarization in W -> tau nu decays with the ATLAS detector in pp collisions at root s=7 TeV

CAPUA, Marcella;Crosetti G;Fazio S;LA ROTONDA, Laura;MASTROBERARDINO, Anna;Meoni E;