학술논문

Search for lepton-flavor-violating $\tau^- \to \mu^-\mu^+\mu^-$ decays at Belle II
Document Type
Working Paper
Author
Belle II CollaborationAdachi, I.Aggarwal, L.Aihara, H.Akopov, N.Aloisio, A.Althubiti, N.Ky, N. AnhAsner, D. M.Atmacan, H.Aushev, V.Aversano, M.Ayad, R.Babu, V.Bae, H.Bahinipati, S.Bambade, P.Banerjee, Sw.Bansal, S.Barrett, M.Baudot, J.Baur, A.Beaubien, A.Becherer, F.Becker, J.Bennett, J. V.Bernlochner, F. U.Bertacchi, V.Bertemes, M.Bertholet, E.Bessner, M.Bettarini, S.Bianchi, F.Bierwirth, L.Bilka, T.Biswas, D.Bobrov, A.Bodrov, D.Bolz, A.Borah, J.Boschetti, A.Bozek, A.Bračko, M.Branchini, P.Browder, T. E.Budano, A.Bussino, S.Campagna, Q.Campajola, M.Cao, L.Casarosa, G.Cecchi, C.Cerasoli, J.Chang, M. -C.Chang, P.Cheaib, R.Cheema, P.Chen, C.Cheon, B. G.Chilikin, K.Chirapatpimol, K.Cho, H. -E.Cho, K.Cho, S. -J.Choi, S. -K.Choudhury, S.Cochran, J.Corona, L.Cui, J. X.Das, S.Dattola, F.De La Cruz-Burelo, E.De La Motte, S. A.De Nardo, G.De Nuccio, M.De Pietro, G.de Sangro, R.Destefanis, M.Dey, S.Dhamija, R.Di Canto, A.Di Capua, F.Dingfelder, J.Doležal, Z.Jiménez, I. DomínguezDong, T. V.Dorigo, M.Dorner, D.Dort, K.Dossett, D.Dreyer, S.Dubey, S.Dugic, K.Dujany, G.Ecker, P.Eliachevitch, M.Feichtinger, P.Ferber, T.Ferlewicz, D.Fillinger, T.Finck, C.Finocchiaro, G.Fodor, A.Forti, F.Frey, A.Fulsom, B. G.Gabrielli, A.Ganiev, E.Garcia-Hernandez, M.Garg, R.Gaudino, G.Gaur, V.Gaz, A.Gellrich, A.Ghevondyan, G.Ghosh, D.Ghumaryan, H.Giakoustidis, G.Giordano, R.Giri, A.Glazov, A.Gobbo, B.Godang, R.Gogota, O.Goldenzweig, P.Gradl, W.Grammatico, T.Granderath, S.Graziani, E.Greenwald, D.Gruberová, Z.Gu, T.Guan, Y.Gudkova, K.Halder, S.Han, Y.Hara, T.Harris, C.Hayasaka, K.Hayashii, H.Hazra, S.Hearty, C.Hedges, M. T.Heidelbach, A.de la Cruz, I. HerediaVillanueva, M. HernándezHiguchi, T.Hoek, M.Hohmann, M.Horak, P.Hsu, C. -L.Humair, T.Iijima, T.Inami, K.Inguglia, G.Ipsita, N.Ishikawa, A.Itoh, R.Iwasaki, M.Jacobs, W. W.Jaffe, D. E.Jang, E. -J.Ji, Q. P.Jia, S.Jin, Y.Junkerkalefeld, H.Kaleta, M.Kalita, D.Kaliyar, A. B.Kandra, J.Kang, K. H.Kang, S.Karyan, G.Kawasaki, T.Keil, F.Kiesling, C.Kim, C. -H.Kim, D. Y.Kim, K. -H.Kim, Y. -K.Kindo, H.Kinoshita, K.Kodyš, P.Koga, T.Kohani, S.Kojima, K.Konno, T.Korobov, A.Korpar, S.Kovalenko, E.Kowalewski, R.Kraetzschmar, T. M. G.Križan, P.Krokovny, P.Kuhr, T.Kulii, Y.Kumar, J.Kumar, M.Kumar, R.Kumara, K.Kunigo, T.Kuzmin, A.Kwon, Y. -J.Lacaprara, S.Lalwani, K.Lam, T.Lanceri, L.Lange, J. S.Laurenza, M.Lautenbach, K.Leboucher, R.Diberder, F. R. LeLee, M. J.Leo, P.Lemettais, C.Levit, D.Lewis, P. M.Li, L. K.Li, S. X.Li, Y.Li, Y. B.Libby, J.Liu, M. H.Liu, Q. Y.Liu, Y.Liu, Z. Q.Liventsev, D.Longo, S.Lueck, T.Lyu, C.Ma, Y.Maggiora, M.Maharana, S. P.Maiti, R.Maity, S.Mancinelli, G.Manfredi, R.Manoni, E.Mantovano, M.Marcantonio, D.Marcello, S.Marinas, C.Martellini, C.Martini, A.Martinov, T.Massaccesi, L.Masuda, M.Matsuoka, K.Matvienko, D.Maurya, S. K.McKenna, J. A.Mehta, R.Meier, F.Merola, M.Metzner, F.Miller, C.Mirra, M.Mitra, S.Miyabayashi, K.Mohanty, G. B.Mondal, S.Moneta, S.Moser, H. -G.Mrvar, M.Mussa, R.Nakamura, I.Nakamura, K. R.Nakao, M.Nakazawa, Y.Charan, A. NarimaniNaruki, M.Narwal, D.Natkaniec, Z.Natochii, A.Nayak, L.Nayak, M.Nazaryan, G.Neu, M.Niebuhr, C.Ninkovic, J.Nishida, S.Ogawa, S.Onishchuk, Y.Ono, H.Otani, F.Pakhlov, P.Pakhlova, G.Pardi, S.Parham, K.Park, H.Park, J.Park, S. -H.Paschen, B.Passeri, A.Patra, S.Paul, S.Pedlar, T. K.Peschke, R.Pestotnik, R.Piccolo, M.Piilonen, L. E.Angioni, G. PinnaPodesta-Lerma, P. L. M.Podobnik, T.Pokharel, S.Praz, C.Prell, S.Prencipe, E.Prim, M. T.Prudiev, I.Purwar, H.Rados, P.Raeuber, G.Raiz, S.Rauls, N.Reif, M.Reiter, S.Reuter, L.Ripp-Baudot, I.Rizzo, G.Robertson, S. H.Roehrken, M.Roney, J. M.Rostomyan, A.Rout, N.Russo, G.Sanders, D. A.Sandilya, S.Santelj, L.Sato, Y.Savinov, V.Scavino, B.Schneider, S.Schwanda, C.Schwickardi, M.Seino, Y.Selce, A.Senyo, K.Serrano, J.Sevior, M. E.Sfienti, C.Shan, W.Sharma, C.Shen, C. P.Shi, X. D.Shillington, T.Shimasaki, T.Shiu, J. -G.Shtol, D.Sibidanov, A.Simon, F.Singh, J. B.Skorupa, J.Smith, K.Sobie, R. J.Sobotzik, M.Soffer, A.Sokolov, A.Solovieva, E.Spataro, S.Spruck, B.Starič, M.Stavroulakis, P.Stefkova, S.Stroili, R.Sue, Y.Sumihama, M.Sumisawa, K.Sutcliffe, W.Suwonjandee, N.Svidras, H.Takahashi, M.Takizawa, M.Tamponi, U.Tanaka, S.Tanida, K.Tenchini, F.Thaller, A.Tittel, O.Tiwary, R.Tonelli, D.Torassa, E.Trabelsi, K.Tsaklidis, I.Ueda, I.Uglov, T.Unger, K.Unno, Y.Uno, K.Uno, S.Urquijo, P.Ushiroda, Y.Vahsen, S. E.van Tonder, R.Varvell, K. E.Veronesi, M.Vinokurova, A.Vismaya, V. S.Vitale, L.Vobbilisetti, V.Volpe, R.Vossen, A.Wach, B.Wakai, M.Wallner, S.Wang, E.Wang, M. -Z.Wang, X. L.Wang, Z.Warburton, A.Watanabe, M.Watanuki, S.Wessel, C.Xu, X. P.Yabsley, B. D.Yamada, S.Yan, W.Yang, S. B.Yelton, J.Yin, J. H.Yook, Y. M.Yoshihara, K.Yuan, C. Z.Zani, L.Zeng, F.Zhang, B.Zhang, Y.Zhilich, V.Zhou, Q. D.Zhou, X. Y.Zhukova, V. I.Žlebčík, R.
Source
Subject
High Energy Physics - Experiment
Language
Abstract
We present the result of a search for the charged-lepton-flavor violating decay $\tau^- \to \mu^-\mu^+\mu^-$ using a $424fb^{-1}$ sample of data recorded by the Belle II experiment at the SuperKEKB $e^{-}e^{+}$ collider. The selection of $e^{-}e^{+}\to\tau^+\tau^-$ events is based on an inclusive reconstruction of the non-signal tau decay, and on a boosted decision tree to suppress background. We observe one signal candidate, which is compatible with the expectation from background processes. We set a $90\%$ confidence level upper limit of $1.9 \times 10^{-8}$ on the branching fraction of the \taumu decay, which is the most stringent bound to date.