Measurement of the τ Michel parameters η and ξκ in the radiative leptonic decay τ - → l - ν τ ν l γ

N. Shimizu, H. Aihara, D. Epifanov, I. Adachi, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, V. Bansa, E. Barberio, V. Bhardwaj, B. Bhuyan, J. Biswal, A. Bobrov, A. Bozek, M. BračkoT. E. Browder, D. Červenkov, M. C. Chang, P. Chang, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, K. Cho, S. K. Choi, Y. Choi, D. Cinabro, T. Czank, N. Dash, S. Di Carlo, Z. Doležal, D. Dutta, S. Eidelman, J. E. Fast, T. Ferber, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, M. Gelb, P. Goldenzweig, D. Greenwald, E. Guido, J. Haba, K. Hayasaka, H. Hayashii, M. T. Hedges, S. Hirose, W. S. Hou, T. Iijima, K. Inami, G. Inguglia, A. Ishikawa, R. Itoh, M. Iwasaki, I. Jaegle, H. B. Jeon, S. Jia, Y. Jin, K. K. Joo, T. Julius, K. H. Kang, G. Karyan, T. Kawasaki, C. Kiesling, D. Y. Kim, J. B. Kim, S. H. Kim, Y. J. Kim, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križan, R. Kroeger, P. Krokovny, R. Kulasiri, A. Kuzmin, Y. J. Kwon, J. S. Lange, I. S. Lee, L. K. Li, Y. Li, L. Li Gioi, J. Libby, D. Liventsev, M. Masuda, M. Merola, K. Miyabayashi, H. Miyata, G. B. Mohanty, H. K. Moon, T. Mori, R. Mussa, E. Nakano, M. Nakao, T. Nanut, K. J. Nath, Z. Natkaniec, M. Nayak, M. Niiyama, N. K. Nisar, S. Nishida, S. Ogawa, S. Okuno, H. Ono, G. Pakhlova, B. Pal, C. W. Park, H. Park, S. Paul, T. K. Pedlar, R. Pestotnik, L. E. Piilonen, V. Popov, M. Ritter, A. Rostomyan, Y. Sakai, M. Salehi, S. Sandilya, Y. Sato, V. Savinov, O. Schneider, G. Schnell, C. Schwanda, Y. Seino, K. Senyo, M. E. Sevior, V. Shebalin, T. A. Shibata, J. G. Shiu, B. Shwartz, A. Sokolov, E. Solovieva, M. Starič, J. F. Strube, K. Sumisawa, T. Sumiyoshi, U. Tamponi, K. Tanida, F. Tenchini, K. Trabelsi, M. Uchida, T. Uglov, Y. Unno, S. Uno, Y. Usov, C. Van Hulse, G. Varner, V. Vorobyev, A. Vossen, C. H. Wang, M. Z. Wang, P. Wang, M. Watanabe, E. Widmann, E. Won, Y. Yamashita, H. Ye, C. Z. Yuan, Z. P. Zhang, V. Zhilich, V. Zhukova, V. Zhulanov, A. Zupanc

Research output: Contribution to journalArticle

Abstract

We present a measurement of the Michel parameters of the τ lepton, η and ξκ, in the radiative leptonic decay τ - → l - ν τ ν l γ using 711 fb -1 of collision data collected with the Belle detector at the KEKB e + e - collider. The Michel parameters are measured in an unbinned maximum likelihood fit to the kinematic distribution of e + e - → τ + τ - → (π + π 0 ν τ )(l - ν τ ν l γ)(l = e or μ The measured values of the Michel parameters are η = -1.3 ± 1.5 ± 0.8 and ξκ = 0.5 ± 0.4 ± 0.2, where the first error is statistical and the second is systematic. This is the first measurement of these parameters. These results are consistent with the Standard Model predictions within their uncertainties, and constrain the coupling constants of the generalized weak interaction.

Original languageEnglish
JournalProgress of Theoretical and Experimental Physics
Volume2018
Issue number2
DOIs
Publication statusPublished - 2018 Feb 1

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Shimizu, N., Aihara, H., Epifanov, D., Adachi, I., Said, S. A., Asner, D. M., Aulchenko, V., Aushev, T., Ayad, R., Babu, V., Badhrees, I., Bakich, A. M., Bansa, V., Barberio, E., Bhardwaj, V., Bhuyan, B., Biswal, J., Bobrov, A., Bozek, A., ... Zupanc, A. (2018). Measurement of the τ Michel parameters η and ξκ in the radiative leptonic decay τ - → l - ν τ ν l γ Progress of Theoretical and Experimental Physics, 2018(2). https://doi.org/10.1093/ptep/pty003