Measurement of τ polarization in W→τν decays with the ATLAS detector in pp collisions at $\sqrt{s} =7~\mathrm{TeV}

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2012-07, Vol.72 (7)
• Main Authors: Almond, J., Antonov, A., Beddall, A., Bee, C. P., Bell, W. H., Bomben, M., Braun, H. M., Bremer, J., Carter, J. R., Casado, M. P., Chafaq, A., Chakraborty, D., Cinca, D., Ciubancan, M., Cogneras, E., Consonni, S. M., Czirr, H., Danielsson, H. O., de Mora, L., Duflot, L., Düren, M., Eckweiler, S., Esposito, B., Federic, P., Feng, C., Ferrara, V., Franchino, S., Frank, T., Garberson, F., Geich-Gimbel, Ch, Giakoumopoulou, V., Glasman, C., Glazov, A., Hartert, J., Hirschbuehl, D., Hoecker, A., Hryn’ova, T., Istin, S., Jeanty, L., Jimenez Belenguer, M., Jin, S., Kadlecik, P., Kawagoe, K., Kazanin, V. A., Kononov, A. I., Konoplich, R., Kwee, R., Lankford, A. J., Leger, A., Lleres, A., Loddenkoetter, T., Losada, M., Lou, X., Maslennikov, A. L., Matricon, P., Maurer, J., Miao, J., Milstein, D., Mir, L. M., Montesano, S., Moore, R. W., Mountricha, E., Mueller, F., Naumann, T., Neal, H. A., Nektarijevic, S., Nelson, T. K., Nickerson, R. B., Niinikoski, T., Nilsson, P., Oh, A., Olariu, A., Olszowska, J., Patel, N., Randle-Conde, A. S., Reeves, K., Rodriguez, D., Rosbach, K., Saxon, J., Scheirich, D., Schwierz, R., Seuster, R., Shaver, L., Simak, V., Slavicek, T., Snyder, S., Stanek, R. W., Steele, G., Stelzer-Chilton, O., Sugimoto, T., Sun, X., Thadome, J., Tsung, J. -W., Ueno, R., Unel, G., Vlasov, N., Wang, T., Wenig, S., Wildt, M. A., Wilson, M. G.
• Format: Article
• Language: English
• Subjects: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 1434-6044; 1434-6052

Here in this paper, a measurement of τ polarization in W→τν decays is presented. It is measured from the energies of the decay products in hadronic τ 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 τ polarization is Pτ= -1.06 ± 0.04 (stat)$+0.05\atop{-0.07}$ (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [-1,-0.91]. Measurements of τ polarization have not previously been made at hadron colliders.