Correlation-Measurements in Z-]Tau(+)tau(-) and the Tau-Neutrino Helicity

Buskulic D, Debonis I, Decamp D, Ghez P, Goy C, Lees JP, Minard MN, Pietrzyk B, Ariztizabal F, Comas P, Crespo JM, Delfino M, Efthymiopoulos I, Fernandez E, Fernandezbosman M, Gaitan V, Garrido L, Mattison T, Pacheco A, Padilla C, Pascual A, Creanza D, Depalma M, Farilla A, Iaselli G, Maggi G, Marinelli N, Natali S, Nuzzo S, Ranieri A, Raso G, Romano F, Ruggieri F, Selvaggi G, Silvestris L, Tempesta P, Zito G, Chai Y, Hu H, Huang D, Huang X, Lin J, Wang T, Xie Y, Xu D, Xu R, Zhang J, Zhang L, Zhao W, Bonvicini G, Boudreau J, Casper D, Drevermann H, Forty RW, Ganis G, Gay C, Girone M, Hagelberg R, Harvey J, Hilgart J, Jacobsen R, Jest B, Knobloch J, Lehraus I, Maggi M, Markou C, Martinez M, Mato P, Meinhard H, Minten A, Miquel R, Moser HG, Palazzi F, Pater JR, Perlas JA, Perrodo P, Pusztaszeri JF, Ranjard F, Rolandi L, Rothberg J, Ruan T, Saich M, Schlatter D, Schmelling M, Sefkow F, Tejessy W, Tomalin IR, Veenhof R, Wachsmuth H, Wasserbaech S, Wiedenmann W, Wildish T, Witzeling W, Wotschack J, Ajaltouni Z, Bardadinotwinowska M, Barres A, Boyer C, Falvard A, Gay P, Guicheney C, Henrard P, Jousset J, Michel B, Montret JC, Pallin D, Perret P, Podlyski F, Proriol J, Saadi F, Fearnley T, Hansen JB, Hansen JD, Hansen JR, Hansen PH, Mollerud R, Nilsson BS, Kyriakis A, Simopoulou E, Siotis I, Vayaki A, Zachariadou K, Badier J, Blondel A, Bonneaud G, Brient JC, Bourdon P, Fouque G, Orteu S, Rouge A, Rumpf M, Tanaka R, Verderi M, Videau H, Candlin DJ, Parsons MI, Veitch E, Focardi E, Moneta L, Parrini G, Corden M, Georgiopoulos C, Jaffe DE, Levinthal D, Antonelli A, Baldini R, Bencivenni G, Bologna G, Bossi F, Campana P, Capon G, Cerutti F, Chiarella V, Felici G, Laurelli P, Mannocchi G, Murtas F, Murtas GP, Passalacqua L, Pepealtarelli M, Colrain P, Tenhave I, Lynch JG, Maitland W, Morton WT, Raine C, Reeves P, Scarr JM, Smith K, Smith MG

Zusammenfassung

Using data collected with the ALEPH detector at LEP correlations between the decay products of the tau(+) and tau- produced in the decay of the Z have been measured. The measurements performed in the decays tau --> pi nu and tau --> p nu place limits on deviations from the Standard Model. These are given by the parameter xi with xi = -1 for the Standard Model. The measured values are xi(pi) = -0.95 +/- 0.11 +/- 0.05 and xi(p) = -1.03 +/- 0.11 +/- 0.05. For models which predict xi(pi) = xi(p) = xi - interpreted as the average tau neutrino helicity - the measurement is xi = -0.99 +/- 0.07 +/- 0.04.