Phys. Rev. D
61,
012002
(1999)
[22 pages]
Hadronic structure in the decay τ-→ντπ-π0π0 and the sign of the tau neutrino helicity
D. M. Asner et al. (CLEO Collaboration)
Show All Authors/Affiliations
Hide All Authors/Affiliations
D. M. Asner, A. Eppich, J. Gronberg, T. S. Hill, D. J. Lange, R. J. Morrison, H. N. Nelson, T. K. Nelson, and D. Roberts
University of California, Santa Barbara, California 93106
B. H. Behrens, W. T. Ford, A. Gritsan, H. Krieg, J. Roy, and J. G. Smith
University of Colorado, Boulder, Colorado 80309-0390
J. P. Alexander, R. Baker, C. Bebek, B. E. Berger, K. Berkelman, V. Boisvert, D. G. Cassel, D. S. Crowcroft, M. Dickson, S. von Dombrowski, P. S. Drell, K. M. Ecklund, R. Ehrlich, A. D. Foland, P. Gaidarev, R. S. Galik, L. Gibbons, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, P. I. Hopman, D. L. Kreinick, T. Lee, Y. Liu, T. O. Meyer, N. B. Mistry, C. R. Ng, E. Nordberg, M. Ogg*, J. R. Patterson, D. Peterson, D. Riley, A. Soffer, J. G. Thayer, P. G. Thies, B. Valant-Spaight, A. Warburton, and C. Ward
Cornell University, Ithaca, New York 14853
M. Athanas, P. Avery, C. D. Jones, M. Lohner, C. Prescot, A. I. Rubiera, J. Yelton, and J. Zheng
University of Florida, Gainesville, Florida 32611
G. Brandenburg, R. A. Briere, A. Ershov, Y. S. Gao, D. Y.-J. Kim, and R. Wilson
Harvard University, Cambridge, Massachusetts 02138
T. E. Browder, Y. Li, J. L. Rodriguez, and H. Yamamoto
University of Hawaii at Manoa, Honolulu, Hawaii 96822
T. Bergfeld, B. I. Eisenstein, J. Ernst, G. E. Gladding, G. D. Gollin, R. M. Hans, E. Johnson, I. Karliner, M. A. Marsh, M. Palmer, C. Plager, C. Sedlack, M. Selen, J. l. Thaler, and J. Williams
University of Illinois, Urbana-Champaign, Illinois 61801
K. W. Edwards
Carleton University, Ottawa, Ontario, Canada K1S 5B6
the Institute of Particle Physics, Canada
A. Bellerive, R. Janicek, and P. M. Patel
McGill University, Montréal, Québec, Canada H3A 2T8
the Institute of Particle Physics, Canada
A. J. Sadoff
Ithaca College, Ithaca, New York 14850
R. Ammar, P. Baringer, A. Bean, D. Besson, D. Coppage, R. Davis, S. Kotov, I. Kravchenko, N. Kwak, X. Zhao, and L. Zhou
University of Kansas, Lawrence, Kansas 66045
S. Anderson, Y. Kubota, S. J. Lee, R. Mahapatra, J. J. O’Neill, R. Poling, T. Riehle, and A. Smith
University of Minnesota, Minneapolis, Minnesota 55455
M. S. Alam, S. B. Athar, Z. Ling, A. H. Mahmood, S. Timm, and F. Wappler
State University of New York at Albany, Albany, New York 12222
A. Anastassov, J. E. Duboscq, K. K. Gan, C. Gwon, T. Hart, K. Honscheid, H. Kagan, R. Kass, J. Lorenc, H. Schwarthoff, A. Wolf, and M. M. Zoeller
Ohio State University, Columbus, Ohio 43210
S. J. Richichi, H. Severini, P. Skubic, and A. Undrus
University of Oklahoma, Norman, Oklahoma 73019
M. Bishai, S. Chen, J. Fast, J. W. Hinson, J. Lee, N. Menon, D. H. Miller, E. I. Shibata, and I. P. J. Shipsey
Purdue University, West Lafayette, Indiana 47907
S. Glenn, Y. Kwon†, A. L. Lyon, and E. H. Thorndike
University of Rochester, Rochester, New York 14627
C. P. Jessop, K. Lingel, H. Marsiske, M. L. Perl, V. Savinov, D. Ugolini, and X. Zhou
Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309
T. E. Coan, V. Fadeyev, I. Korolkov, Y. Maravin, I. Narsky, R. Stroynowski, J. Ye, and T. Wlodek
Southern Methodist University, Dallas, Texas 75275
M. Artuso, S. Ayad, E. Dambasuren, S. Kopp, G. Majumder, G. C. Moneti, R. Mountain, S. Schuh, T. Skwarnicki, S. Stone, A. Titov, G. Viehhauser, and J. C. Wang
Syracuse University, Syracuse, New York 13244
S. E. Csorna, K. W. McLean, S. Marka, and Z. Xu
Vanderbilt University, Nashville, Tennessee 37235
R. Godang, K. Kinoshita‡, I. C. Lai, P. Pomianowski, and S. Schrenk
Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
G. Bonvicini, D. Cinabro, R. Greene, L. P. Perera, and G. J. Zhou
Wayne State University, Detroit, Michigan 48202
S. Chan, G. Eigen, E. Lipeles, M. Schmidtler, A. Shapiro, W. M. Sun, J. Urheim, A. J. Weinstein, and F. Würthwein
California Institute of Technology, Pasadena, California 91125
D. E. Jaffe, G. Masek, H. P. Paar, E. M. Potter, S. Prell, and V. Sharma
University of California, San Diego, La Jolla, California 92093
(CLEO Collaboration)
Received 16 February 1999; published 6 December 1999
Based on a sample corresponding to 4.3×106 produced τ-pair events, we have studied hadronic dynamics in the decay τ-→ντπ-π0π0 in data recorded by the CLEO II detector operating at the CESR e+e- collider. The decay is dominated by the process τ-→ντa1-(1260), with the a1- meson decaying to three pions predominantly via the lowest dimensional (mainly S-wave) ρ-π0 Born amplitude. From model-dependent fits to the Dalitz plot and angular observables in bins of 3π mass, we find significant additional contributions from amplitudes for a1 decay to σπ, f0(1370)π, and f2(1270)π, as well as higher dimensional a1→ρπ and ρ′π amplitudes. Notably, the squared σπ amplitude accounts for approximately 15% of the total τ-→ντπ-π0π0 rate in the models considered. The data are well described using couplings to these amplitudes that are independent of the 3π mass. These amplitudes also provide a good description for the τ-→ντπ-π+π- Dalitz plot distributions. We have searched for additional contributions from τ-→ντπ′-(1300). We place 90% confidence level upper limits on the branching fraction for this channel of between 1.0×10-4 and 1.9×10-4, depending on the π′ decay mode considered. The π-π0π0 mass spectrum is parametrized by a Breit-Wigner form with a mass-dependent width which is specified according to the results of the Dalitz plot fits plus an unknown coupling to an a1→K*K amplitude. From a χ2 fit using this parametrization, we extract the pole mass and width of the a1, as well as the magnitude of the K*K coupling. We have also investigated the impact of a possible contribution from the a1′(1700) meson on this spectrum. Finally, exploiting the parity-violating angular asymmetry in a1→3π decay, we determine the signed value of the τ neutrino helicity to be hντ=-1.02±0.13 (stat)±0.03 (syst+model), confirming the left-handedness of the τ neutrino.
© 1999 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevD.61.012002
DOI:
10.1103/PhysRevD.61.012002
PACS:
13.35.Dx, 13.25.Jx, 14.40.Cs, 14.60.Fg
*Permanent address: University of Texas, Austin, TX 78712. †Permanent address: Yonsei University, Seoul 120-749, Korea. ‡Permanent address: University of Cincinnati, Cincinnati, OH 45221
|
|
