1. A determination of two Michel parameters in purely leptonic tau decays
- Author
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Albrecht, H., Ehrlichmann, H., Wurth, R., Hast, C., Kolanoski, H., Kosche, A., Lange, A., Lindner, A., Mankel, R., Schieber, M., Siegmund, T., Spaan, B., Hamacher, T., Thurn, H., Töpfer, D., Wegener, D., Bittner, M., Eckstein, P., Paulini, M., Reim, K., Wegener, H., Eckmann, R., Mundt, R., Hofmann, R. P., Oest, T., Reiner, R., Schmidt-Parzefall, W., Funk, W., Stiewe, J., Werner, S., Ehret, K., Hofmann, W., Hüpper, A., Khan, S., Kirchhoff, A., Knöpfle, K. T., Seeger, M., Spengler, J., Britton, D. I., Charlesworth, C. E. K., Edwards, K. W., Hyatt, E. R. F., Kapitza, H., Krieger, P., MacFarlane, D. B., Nau, A., Patel, P. M., Prentice, J. D., Saull, P. R. B., Tzamariudaki, K., Van de Water, R. G., Yoon, T.-S., Reβing, D., Schmidtler, M., Schneider, M., Schubert, K. R., Nowak, S., Strahl, K., Waldi, R., Weseler, S., Kernel, G., Križan, P., Križnič, E., Podobnik, T., Živko, T., Balagura, V., Belyaev, I., Schröder, H., Chechelnitsky, S., Danilov, M., Droutskoy, A., Gershtein, Yu., Golutvin, A., Kostina, G., Litvintsev, D., Lubimov, V., Pakhlov, P., Ratnikov, F., Schulz, H. D., Semenov, S., Snizhko, A., Soloshenko, V., Tichomirov, I., Zaitsev, Yu., ARGUS Collaboration, and Walter, M.
- Subjects
annihilation: electron positron ,electroproduction: tau ,correlation [momentum] ,ARGUS ,DESY DORIS Stor ,10 GeV ,annihilation [electron positron] ,leptonic decay [tau] ,electron positron: annihilation ,(muon electron) [correlation] ,electroproduction [tau] ,pair production: tau ,ddc:530 ,S035.2 ,electron positron [colliding beams] ,+muon+electron+4neutrino%22">tau+ tau- --> muon electron 4neutrino ,S035.1 ,S035RHE ,electron positron [annihilation] ,tau: pair production ,leptonic decay: tau ,tau [pair production] ,correlation: (muon electron) ,Michel parameter ,momentum: correlation ,S035RHM ,electron positron: colliding beams ,S035XI ,tau [electroproduction] ,pair production [tau] ,colliding beams: electron positron ,tau: electroproduction ,tau: leptonic decay ,colliding beams [electron positron] ,tau [leptonic decay] ,experimental results - Abstract
9 pp. (1993)., Using the ARGUS detector at the e+e− storage ring DORIS II, we have determined the Michel parameters ϱ and ξ of τ → μννandτ → eνν decays. From a data sample with 333 events/pb around s= 10GeV, we select 3230 events ǂe+e−→ τ+τ−→ (μ±μμ)(eǂvv) and determine ϱ from the e and μ momentum spectra and ξ from the correlations between e and μ momenta. For ϱ we obtain ϱτ→e = 0.79 ± 0.08 ± 0.06 and ϱτ→μ = 0.76 ± 0.08 in accordance with the V - A structure of the decays. The momentum correlations are only sensitive to the product ξτ→eξτ→μ. Setting ξτ→e = ξτ→μ, we obtain |ξτ| = 0.90 ± 0.15 ± 0.10 also in accordance with V - A. The updated decay fractions are B(τ →evv) = (17.5 ± 0.3 ± 0.5)% and B(τ → μvv) = (17.4 ± 0.3 ± 0.5)%.
- Published
- 1993
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