Determination of the Michel parameters and the τ neutrino helicity in τ decay

Using the CLEO II detector at the e{sup +}e{sup -} storage ring CESR, we have determined the Michel parameters {rho}, {zeta}, and {delta} in {tau}{sup {-+}}{nu}{bar {nu}} decay as well as the {tau} neutrino helicity parameter H{sub {nu}{sub {tau}}} in {tau}{sup {-+}}{pi}{sup 0}{nu} decay. From a data sample of 3.02 x 10{sup 6} {tau} pairs produced at {radical}s = 10.6 GeV, using events of the topology e{sup +}e{sup -} {yields} {tau}{sup +}{tau}{sup -} {yields} (l{sup {+-}}{nu}{bar {nu}})({pi}{sup {-+}}{pi}{sup 0}{nu}) and e{sup +}e{sup -} {yields} {tau}{sup +}{tau}{sup -} {yields} ({pi}{sup {+-}}{pi}{sup 0}{bar {nu}})({pi}{sup {-+}}{pi}{sup 0}{nu}), and the determined sign of h{sub {nu}{sub {tau}}} [1,2], the combined result of the three samples is: {rho} = 0.747 {+-} 0.010 {+-} 0.006, {zeta} = 1.007 {+-} 0.040 {+-} 0.015, {zeta}{delta} = 0.745 {+-}0.026 {+-}0.009, and h{sub {nu}{sub {tau}}} = -0.995 {+-} 0.010 {+-} 0.003. The results are in agreement with the Standard Model V-A interaction.

Harold S. Park | A. Anastassov | K. Cho | K. Honscheid | R. Kass | S. Márka | D. Ugolini | S. Anderson | B. Barish | F. Frasconi | A. Weinstein | D. Besson | J. Thaler | D. Cinabro | J. Ye | V. Fadeyev | T. Coan | M. Alam | G. Brandenburg | G. Eigen | K. Gan | V. Jain | H. Kagan | I. Korolkov | S. Kotov | T. Nelson | S. Prell | H. Severini | P. Skubic | A. Soffer | R. Stroynowski | A. Undrus | C. Ward | R. Greene | T. Browder | P. Drell | C. Bebek | A. Bellerive | Varun Sharma | F. Würthwein | J. Richman | W. Ford | J. Alexander | L. Gibbons | B. Heltsley | J. Patterson | A. Ryd | P. Avery | J. Yelton | P. Baringer | A. Bean | Y. Maravin | J. Gronberg | D. Lange | Y. Kubota | R. Godang | L. Perera | K. Bloom | I. Kravchenko | C. Jessop | D. Miller | I. Shipsey | K. Ecklund | I. Volobouev | D. Asner | Jongseo Lee | Y. Gao | S. Schrenk | M. Perl | R. Poling | Hitoshi Yamamoto | Youngjoon Kwon | G. Gollin | E. Johnson | R. Galik | G. Bonvicini | M. Palmer | D. Riley | A. Smith | R. Kutschke | S. Gray | S. Patton | R. Wanke | Harold S Park | M. Bishai | A. Foland | J. Miller | M. Zoeller | J. Ernst | B. Valant-Spaight | S. Lee | R. Briere | D. Kim | K. Kinoshita | D. Peterson | S. Glenn | P. Gaidarev | K. Berkelman | Xingjiang Zhou | S. D. Johnson | H. Paar | F. Li | H. Marsiske | T. Skwarnicki | H. Nelson | S. Schuh | E. Thorndike | P. Hopman | S. Stone | M. Artuso | R. Mountain | S. Menary | M. Witherell | I. Narsky | D. Cassel | J. Duboscq | C. Jones | D. Coppage | A. Mahmood | S. Timm | F. Wappler | M. Selen | J. Roy | J. Zheng | N. Mistry | B. Berger | S. Kopp | J. Urheim | C. Darling | V. Shelkov | D. Macfarlane | P. Rankin | P. Patel | R. Ehrlich | Yehan Liu | K. W. Edwards | D. Hartill | D. Kreinick | A. Sadoff | S. Athar | B. Nemati | Z. Ling | A. Efimov | M. Gao | C. Ng | J. Bartelt | P. Kim | N. Kwak | R. Ammar | G. Masek | R. Morrison | B. Gittelman | J. Kandaswamy | E. Nordberg | G. Viehhauser | C. Prescott | B. Eisenstein | R. M. Hans | I. Karliner | M. A. Marsh | T. Hart | S. Richichi | V. Savinov | J. W. Hinson | E. Shibata | S. Csorna | T. Hill | M. Goldberg | M. Athanas | R. Janicek | G. Moneti | G. Gladding | J. Smith | M. Schmidtler | M. Lattery | R. J. Morrison | J. Staeck | M. B. Spencer | T. Riehle | D. Fujino | M. Sung | A. Wolf | J. Fast | N. Menon | M. Yurko | S. Roberts | K. Lingel | D. He | X. Xing | K. W. McLean | I. Lai | P. Pomianowski | G. Zhou | M. Chadha | S. Chan | D. Roberts | B. Behrens | D. S. Crowcroft | M. Dickson | T. Lee | M. Ogg | M. Lohner | T. Bergfeld | G. S. Ludwig | Richard K. Wilson | C. O'grady | D. Bliss | R. Balest | J. O’Neill | W. Ross | N. Hancock | S. Blinov | E. Gerndt | C. Qiao | H. Cho | D. Coffman | J. Masui | J. Mevissen | Robin E. P. Davis | M. Wood | R. Elia | K. D. Fisher | W. Brower | Yan Li | Javier Rodriguez | Raymond Wang | R. Mountain | R. Davis | S. Prell | D. Miller | S. J. Lee | H. Yamamoto | D. MacFarlane | J. Zheng | F. Li

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