The polarisation of $\tau$'s produced in Z decay is measured using 160 pb$^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068 $ and ${\cal A}_{\tau} = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of $e$-$\tau$ universality. Assuming universality, the value ${\cal A}_{e{-}\tau} = 0.1474 \pm 0.0045$ is obtained from which the effective weak mixing angle $\sin^2 {\theta_{\mathrm{W}}^{\mathrm{eff}}} =0.23147 \pm 0.00057 $ is derived.

Measurement of the tau polarization at LEP / A. Heister, S. Schael, R. Barate, I. De Bonis, D. Decamp, Philippe Ghez, C. Goy, J.P. Lees, E. Merle, M.N. Minard, B. Pietrzyk, R. Alemany, S. Bravo, M.P. Casado, M. Chmeissani, J.M. Crespo, E. Fernandez, M. Fernandez-Bosman, L. Garrido, E. Grauges, M. Martinez, G. Merino, R. Miquel, L.M. Mir, A. Pacheco, H. Ruiz, A. Colaleo, D. Creanza, M. de Palma, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito, X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao, D. Abbaneo, P. Azzurri, G. Boix, O. Buchmuller, M. Cattaneo, F. Cerutti, B. Clerbaux, G. Dissertori, H. Drevermann, R.W. Forty, M. Frank, T.C. Greening, J.B. Hansen, John Harvey, P. Janot, B. Jost, M. Kado, P. Mato, A. Moutoussi, F. Ranjard, Gigi Rolandi, D. Schlatter, M. Schmitt, O. Schneider, P. Spagnolo, W. Tejessy, F. Teubert, E. Tournefier, J. Ward, A.E. Wright, Z. Ajaltouni, F. Badaud, A. Falvard, P. Gay, P. Henrard, J. Jousset, B. Michel, S. Monteil, J.C. Montret, D. Pallin, P. Perret, F. Podlyski, J.D. Hansen, J.R. Hansen, P.H. Hansen, B.S. Nilsson, A. Waananen, G. Daskalakis, A. Kyriakis, C. Markou, E. Simopoulou, A. Vayaki, A. Blondel, G. Bonneaud, J.C. Brient, A. Rouge, M. Rumpf, M. Swynghedauw, M. Verderi, H. Videau, E. Focardi, G. Parrini, K. Zachariadou, A. Antonelli, M. Antonelli, G. Bencivenni, G. Bologna, F. Bossi, P. Campana, G. Capon, V. Chiarella, P. Laurelli, G. Mannocchi, F. Murtas, G.P. Murtas, L. Passalacqua, M. Pepe-Altarelli, A.W. Halley, J.G. Lynch, P. Negus, V. O'Shea, C. Raine, A.S. Thompson, S. Wasserbaech, R. Cavanaugh, S. Dhamotharan, C. Geweniger, P. Hanke, G. Hansper, V. Hepp, E.E. Kluge, A. Putzer, J. Sommer, K. Tittel, S. Werner, M. Wunsch, R. Beuselinck, D.M. Binnie, W. Cameron, P.J. Dornan, M. Girone, N. Marinelli, J.K. Sedgbeer, J.C. Thompson, V.M. Ghete, P. Girtler, E. Kneringer, D. Kuhn, G. Rudolph, E. Bouhova-Thacker, C.K. Bowdery, A.J. Finch, F. Foster, G. Hughes, R.W.L. Jones, M.R. Pearson, N.A. Robertson, I. Giehl, K. Jakobs, K. Kleinknecht, G. Quast, B. Renk, E. Rohne, H.G. Sander, H. Wachsmuth, C. Zeintiz, A. Bonissent, J. Carr, P. Coyle, O. Leroy, P. Payre, D. Rousseau, M. Talby, M. Aleppo, F. Ragusa, A. David, H. Dietl, G. Ganis, K. Huttmann, G. Lutjens, C. Mannert, W. Manner, H.G. Moser, R. Settles, H. Stenzel, W. Wiedenmann, G. Wolf, J. Boucrot, O. Callot, S. Chen, M. Davier, L. Duflot, J.F. Grivaz, P. Heusse, A. Jacholkowska, J. Lefrancois, Irina Nikolic, J.J. Veillet, I. Videau, C. Yuan, Giuseppe Bagliesi, T. Boccali, G. Calderini, V. Ciulli, L. Foa, A. Giassi, F. Ligabue, A. Messineo, F. Palla, G. Sanguinetti, A. Sciaba, G. Sguazzoni, R. Tenchini, A. Venturi, P.G. Verdini, G.A. Blair, G. Cowan, M.G. Green, T. Medcalf, J.A. Strong, P. Teixeira-Dias, J.H. von Wimmersperg-Toeller, R.W. Clifft, T.R. Edgecock, P.R. Norton, I.R. Tomalin, Brigitte Bloch-Devaux, P. Colas, S. Emery, W. Kozanecki, E. Lancon, M.C. Lemaire, E. Locci, P. Perez, J. Rander, J.F. Renardy, A. Roussarie, J.P. Schuller, J. Schwindling, A. Trabelsi, B. Vallage, N. Konstantinidis, A.M. Litke, G. Taylor, C.N. Booth, S. Cartwright, F. Combley, M. Lehto, L.F. Thompson, K. Affholderbach, Armin Boehrer, S. Brandt, C. Grupen, A. Misiejuk, A. Ngac, G. Prange, U. Sieler, G. Giannini, J. Rothberg, S.R. Armstrong, K. Cranmer, P. Elmer, D.P.S. Ferguson, Y. Gao, S. Gonzalez, O.J. Hayes, H. Hu, S. Jin, J. Kile, P.A. McNamara,, III, J. Nielsen, W. Orejudos, Y.B. Pan, Y. Saadi, I.J. Scott, J. Walsh, Sau Lan Wu, X. Wu, G. Zobernig. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 20:3(2001), pp. 401-430. [10.1007/s100520100689]

Measurement of the tau polarization at LEP

M. Aleppo;F. Ragusa;
2001

Abstract

The polarisation of $\tau$'s produced in Z decay is measured using 160 pb$^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068 $ and ${\cal A}_{\tau} = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of $e$-$\tau$ universality. Assuming universality, the value ${\cal A}_{e{-}\tau} = 0.1474 \pm 0.0045$ is obtained from which the effective weak mixing angle $\sin^2 {\theta_{\mathrm{W}}^{\mathrm{eff}}} =0.23147 \pm 0.00057 $ is derived.
elementary particle physics ; high energy ; LEP ; accelerator ; standard model
Settore FIS/01 - Fisica Sperimentale
2001
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/148946
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