A measurement of τ polarization at LEP

• Published in: Physics letters. B Vol. 341; no. 2; pp. 245 - 256
• Main Authors: Aloisio, A., Ambrosi, G., Alkhazov, G., Bakken, J.A., Ball, R.C., Banerjee, S., Barillère, R., Bay, A., Bilei, G.M., Bizzarri, R., Bouwens, B., Cai, X.D., Casaus, J., Castello, R., Chaturvedi, U.K., Chen, A., Chen, G., Chen, M., Chien, C.Y., Colino, N., Cui, X.T., Cui, X.Y., Dionisi, C., Dova, M.T., Fabbretti, R., Falciano, S., Fisher, P.H., Gallo, E., Gheordanescu, N., Giagu, S., Gonzalez, E., Gratta, G., Guanziroli, M., Hauschildt, D., Hervé, A., Hilgers, K., Hofer, H., Ille, B., Janssen, H., Jin, B.N., Khokhar, S., Kinnison, W.W., Kornadt, O., Lanske, D., Lanzano, S., Lebrun, P., Leonardi, E., Lin, W.T., Lu, Y.S., Luci, C., Luckey, D., Luminari, L., Maity, M., Malik, R., Mangla, S., Maolinbay, M., Mele, S., Meschini, M., Mihul, A., Monaco, V., Morand, R., Organtini, G., Pieri, M., Plyaskin, V., Rahal-Callot, G., Razis, P., Read, K., Riemann, S., Riemers, B.C., Riles, K., Robohm, A., Röhner, S., Sauvage, G., Scholz, N., Schreiber, H.J., Schwering, G., Scott, I., Sehgal, R., Sheer, I., Son, D., Steuer, M., Stone, H., Strauch, K., Susinno, G.F., Suter, H., Timellini, R., Urbán, L., Van de Walle, R.T., Vorobyov, An.A., Vuilleumier, L., Wadhwa, M., Wallraff, W., Xu, Z.Z., Yang, C.G., Yzerman, M., Zeng, M., Zhang, D.H., Zhang, Z.P., Zhou, G.J., Zhu, R.Y.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 29.12.1994; Elsevier
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/0370-2693(94)90316-6

With a data sample of 86 000 Z → τ +τ −(γ) events collected in 1990 through 1993 we have measured the polarization of τ-leptons as a function of the production polar angle using the following 1-prong τ decay modes: τ −→ e − v ev τ, τ −→π − (K −)v τ, τ −→ϱ −v τ and τ −→a 1 −v τ . We obtain for the ratio vector to axial-vector weak neutral couplings for electrons g Ve / g Ae =0.0791±0.0099(stat)±0.0025 (syst) and taus g Vτ / g Aτ =0.0752±0.0063 (stat)±0.0045 (syst) consistent with the hypothesis of e - τ universality. Assuming universality of the e - τ neutral current we determine the effective electroweak mixing angle to be sin 2 θ eff w = 0.2309 ± 0.0016.