Precision neutral current asymmetry parameter measurements from the Tau polarization at LEP

G. Abbiendi, C. Ainsley, P. F. Akesson, G. Alexander, J. Allison, G. Anagnostou, K. J. Anderson, S. Arcelli, S. Asai, D. Axen, G. Azuelos, I. Bailey, A. H. Ball, E. Barberio, R. J. Barlow, R. J. Batley, T. Behnke, K. W. Bell, G. Bella, A. BelleriveG. Benelli, S. Bethke, O. Biebel, I. J. Bloodworth, O. Boeriu, P. Bock, J. Böhme, D. Bonacorsi, M. Boutemeur, S. Braibant, L. Brigliadori, R. M. Brown, H. J. Burckhart, J. Cammin, P. Capiluppi, R. K. Carnegie, B. Caron, A. A. Carter, J. R. Carter, C. Y. Chang, D. G. Charlton, P. E.L. Clarke, E. Clay, I. Cohen, J. Couchman, A. Csilling, M. Cuffiani, S. Dado, G. M. Dallavalle, S. Dallison, A. de Roeck, E. A. de Wolf, P. Dervan, K. Desch, B. Dienes, M. S. Dixit, M. Donkers, J. Dubbert, E. Duchovni, G. Duckeck, I. P. Duerdoth, P. G. Estabrooks, E. Etzion, F. Fabbri, M. Fanti, L. Feld, P. Ferrari, F. Fiedler, I. Fleck, M. Ford, A. Frey, A. Fürtjes, D. I. Futyan, P. Gagnon, J. W. Gary, G. Gaycken, C. Geich-Gimbel, G. Giacomelli, P. Giacomelli, D. Glenzinski, J. Goldberg, C. Grandi, K. Graham, E. Gross, J. Grunhaus, M. Gruwé, P. O. Günther, A. Gupta, C. Hajdu, G. G. Hanson, K. Harder, A. Harel, M. Harin-Dirac, M. Hauschild, C. M. Hawkes, R. Hawkings, R. J. Hemingway, C. Hensel, G. Herten, R. D. Heuer, J. C. Hill, K. Hoffman, R. J. Homer, A. K. Honma, D. Horváth, K. R. Hossain, R. Howard, P. Hüntemeyer, P. Igo-Kemenes, K. Ishii, A. Jawahery, H. Jeremie, C. R. Jones, P. Jovanovic, T. R. Junk, N. Kanaya, J. Kanzaki, G. Karapetian, D. Karlen, V. Kartvelishvili, K. Kawagoe, T. Kawamoto, R. K. Keeler, R. G. Kellogg, B. W. Kennedy, D. H. Kim, K. Klein, A. Klier, S. Kluth, T. Kobayashi, M. Kobel, T. P. Kokott, Sachio Komamiya, R. V. Kowalewski, T. Kämer, T. Kress, P. Krieger, J. von Krogh, D. Krop, T. Kuhl, M. Kupper, P. Kyberd, G. D. Lafferty, H. Landsman, D. Lanske, I. Lawson, J. G. Layter, A. Leins, D. Lellouch, J. Letts, L. Levinson, R. Liebisch, J. Lillich, C. Littlewood, A. W. Lloyd, S. L. Lloyd, F. K. Loebinger, G. D. Long, M. J. Losty, J. Lu, J. Ludwig, A. Macchiolo, A. Macpherson, W. Mader, S. Marcellini, T. E. Marchant, A. J. Martin, J. P. Martin, G. Martinez, T. Mashimo, P. Mättig, W. J. McDonald, J. McKenna, T. J. McMahon, R. A. McPherson, F. Meijers, P. Mendez-Lorenzo, W. Menges, F. S. Merritt, H. Mes, A. Michelini, S. Mihara, G. Mikenberg, D. J. Miller, W. Mohr, A. Montanari, T. Mori, K. Nagai, I. Nakamura, H. A. Neal, R. Nisius, S. W. O'Neale, F. G. Oakham, F. Odorici, A. Oh, A. Okpara, M. J. Oreglia, S. Orito, C. Pahl, G. Pásztor, J. R. Pater, G. N. Patrick, J. E. Pilcher, J. Pinfold, D. E. Plane, B. Poli, J. Polok, O. Pooth, A. Quadt, K. Rabbertz, C. Rembser, P. Renkel, H. Rick, N. Rodning, J. M. Roney, S. Rosati, K. Roscoe, A. M. Rossi, Y. Rozen, K. Runge, O. Runolfsson, D. R. Rust, K. Sachs, T. Saeki, O. Sahr, E. K.G. Sarkisyan, C. Sbarra, A. D. Schaile, O. Schaile, P. Scharff-Hansen, M. Schröder, M. Schumacher, C. Schwick, W. G. Scott, R. Seuster, T. G. Shears, B. C. Shen, C. H. Shepherd-Themistocleous, P. Sherwood, G. P. Siroli, A. Skuja, A. M. Smith, G. A. Snow, R. Sobie, S. Söldner-Rembold, S. Spagnolo, F. Spano, M. Sproston, A. Stahl, K. Stephens, D. Strom, R. Ströhmer, L. Stumpf, B. Surrow, S. D. Talbot, S. Tarem, M. Tasevsky, R. J. Taylor, R. Teuscher, J. Thomas, M. A. Thomson, E. Torrence, S. Towers, D. Toya, T. Trefzger, I. Trigger, Z. Trócsányi, E. Tsur, M. F. Turner-Watson, I. Ueda, B. Vachon, C. F. Vollmer, P. Vannerem, M. Verzocchi, H. Voss, J. Vossebeld, D. Waller, C. P. Ward, D. R. Ward, P. M. Watkins, A. T. Watson, N. K. Watson, P. S. Wells, T. Wengler, N. Wermes, D. Wetterling, J. S. White, G. W. Wilson, J. A. Wilson, T. R. Wyatt, S. Yamashita, V. Zacek, D. Zer-Zion

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Abstract

Measurements of the τ lepton polarization and forward-backward polarization asymmetry near the Z0 resonance using the OPAL detector are described. The measurements are based on analyses of τ → eνeντ, τ → μνμντ, τ → πντ, τ → ρντ, and τ → a1ντ decays from a sample of 144,810 e+e- → τ+τ- candidates corresponding to an integrated luminosity of 151 pb-1. Assuming that the τ lepton decays according to V-A theory, we measure the average τ polarization near √s = Mz to be 〈Pτ〉 = (-14.10 ± 0.73 ± 0.55)% and the τ polarization forward-backward asymmetry to be AFB pol = (-10.55 ± 0.76 ± 0.25)%, where the first error is statistical and the second systematic. Taking into account the small effects of the photon propagator, photon-Z0 interference and photonic radiative corrections, these results can be expressed in terms of the lepton neutral current asymmetry parameters: Aτ = 0.1456 ± 0.0076 ± 0.0057, Ae = 0.1454 ± 0.0108 ± 0.0036. These measurements are consistent with the hypothesis of lepton universality and combine to give A = 0.1455±0.0073. Within the context of the Standard Model this combined result corresponds to = 0.23172± 0.00092. Combing these results with those from the other OPAL neutral current measurements yields a value of = 0.23211 ± 0.00068.

Original languageEnglish
Pages (from-to)1-21
Number of pages21
JournalEuropean Physical Journal C
Volume21
Issue number1
Publication statusPublished - 2001 Jan 1
Externally publishedYes

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ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

Cite this

Abbiendi, G., Ainsley, C., Akesson, P. F., Alexander, G., Allison, J., Anagnostou, G., Anderson, K. J., Arcelli, S., Asai, S., Axen, D., Azuelos, G., Bailey, I., Ball, A. H., Barberio, E., Barlow, R. J., Batley, R. J., Behnke, T., Bell, K. W., Bella, G., ... Zer-Zion, D. (2001). Precision neutral current asymmetry parameter measurements from the Tau polarization at LEP. European Physical Journal C, 21(1), 1-21.