The Michel parameter for the decay τ→eνν

H. Janssen, D. Antreasyan, H. W. Bartels, D. Besset, Ch Bieler, J. K. Bienlein, A. Bizzeti, E. D. Bloom, I. Brock, K. Brockmüller, R. Cabenda, A. Cartacci, M. Cavalli-Sforza, R. Clare, A. Compagnucci, G. Conforto, S. Cooper, R. Cowan, D. Coyne, A. EnglerK. Fairfield, G. Folger, A. Fridman, J. Gaiser, D. Gelphman, G. Glaser, G. Godfrey, K. Graaf, F. H. Heimlich, F. H. Heinsius, R. Hofstadter, J. Irion, Z. Jakubowski, K. Karch, S. Keh, T. Kiel, H. Kilian, I. Kirkbride, T. Kloiber, M. Kobel, W. Koch, A. C. König, K. Königsmann, R. W. Krämer, S. Krüger, G. Landi, R. Lee, S. Leffler, R. Lekebusch, A. M. Litke, W. Lockman, S. Lowe, B. Lurz, D. Marlow, H. Marsiske, W. Maschmann, P. McBride, H. Meyer, B. Muryn, F. Messing, W. J. Metzger, B. Monteleoni, R. Nernst, B. Niczyporuk, G. Nowak, C. Peck, P. G. Pelfer, B. Pollock, F. C. Porter, D. Prindle, P. Ratoff, M. Reidenbach, B. Renger, C. Rippich, M. Scheer, P. Schmitt, J. Schotanus, J. Schütte, A. Schwarz, D. Sievers, T. Skwarnicki, V. Stock, K. Strauch, U. Strohbusch, J. Tompkins, H. J. Trost, B. Van Uitert, R. T. Van De Walle, H. Vogel, A. Voigt, U. Volland, K. Wachs, K. Wacker, W. Walk, H. Wegener, D. A. Williams, P. Zschorsch

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10 Scopus citations

Abstract

The Crystal Ball detector at the Doris II storage ring at DESY has been used to study the electron energy spectrum of the decay τ→evv̄. In the standard model the Lorentz structure of the decay matrix element is of the well known V-A type, resulting in a Michel parameter of p=0.75. Our spectrum is found to be consistent with this value. A fit yields the value of 0.64±0.07.

Original languageEnglish (US)
Pages (from-to)273-280
Number of pages8
JournalPhysics Letters B
Volume228
Issue number2
DOIs
StatePublished - Sep 14 1989
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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