학술논문

First measurement of $R(X_{\tau/\ell})$ as an inclusive test of the $b \to c \tau \nu$ anomaly
Document Type
Working Paper
Author
Belle II CollaborationAdachi, I.Adamczyk, K.Aggarwal, L.Ahmed, H.Aihara, H.Akopov, N.Aloisio, A.Asner, D. M.Atmacan, H.Aushev, T.Aushev, V.Aversano, M.Babu, V.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.Bhuyan, B.Bianchi, F.Bilka, T.Bilokin, S.Biswas, D.Bobrov, A.Bodrov, D.Bolz, A.Bondar, A.Bozek, A.Bračko, M.Branchini, P.Briere, R. A.Browder, T. E.Budano, A.Bussino, S.Campajola, M.Cao, L.Casarosa, G.Cecchi, C.Cerasoli, J.Chang, M. -C.Chang, P.Cheema, P.Cheon, B. G.Chilikin, K.Chirapatpimol, K.Cho, H. -E.Cho, K.Cho, S. -J.Choi, S. -K.Choudhury, S.Corona, L.Cremaldi, L. M.Dattola, F.De La Cruz-Burelo, E.De La Motte, S. A.de Marino, G.De Nardo, G.De Nuccio, M.De Pietro, G.de Sangro, R.Destefanis, M.Dhamija, R.Di Canto, A.Di Capua, F.Dingfelder, J.Doležal, Z.Dong, T. V.Dorigo, M.Dort, K.Dreyer, S.Dubey, S.Dujany, G.Ecker, P.Eliachevitch, M.Epifanov, D.Feichtinger, P.Ferber, T.Ferlewicz, D.Fillinger, T.Finocchiaro, G.Fodor, A.Forti, F.Frey, A.Fulsom, B. G.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.Gobbo, B.Godang, R.Gogota, O.Goldenzweig, P.Gradl, W.Grammatico, T.Granderath, S.Graziani, E.Greenwald, D.Gruberová, Z.Gu, T.Gudkova, K.Halder, S.Han, Y.Hara, T.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.Ipsita, N.Ishikawa, A.Itoh, R.Iwasaki, M.Jackson, P.Jacobs, W. W.Jaffe, D. E.Jang, E. -J.Jia, S.Jin, Y.Joo, K. K.Junkerkalefeld, H.Kalita, D.Kaliyar, A. B.Kandra, J.Kang, K. H.Karyan, G.Kawasaki, T.Keil, F.Kiesling, C.Kim, C. -H.Kim, D. Y.Kim, K. -H.Kim, Y. -K.Kinoshita, K.Kodyš, P.Koga, T.Kohani, S.Kojima, K.Korobov, A.Korpar, S.Kovalenko, E.Kowalewski, R.Kraetzschmar, T. M. G.Križan, P.Krokovny, P.Kuhr, T.Kulii, Y.Kumar, M.Kumara, K.Kunigo, T.Kuzmin, A.Kwon, Y. -J.Lacaprara, S.Lam, T.Lanceri, L.Lange, J. S.Laurenza, M.Leboucher, R.Diberder, F. R. LeLee, M. J.Levit, D.Lewis, P. M.Li, L. K.Li, Y.Li, Y. B.Libby, J.Liu, M.Liu, Q. Y.Liu, Z. Q.Liventsev, D.Longo, S.Lueck, T.Luo, T.Lyu, C.Ma, Y.Maggiora, M.Maharana, S. P.Maiti, R.Maity, S.Mancinelli, G.Manfredi, R.Manoni, E.Manthei, A. C.Mantovano, M.Marcantonio, D.Marcello, S.Marinas, C.Martel, L.Martellini, C.Martinov, T.Massaccesi, L.Masuda, M.Matsuda, T.Matsuoka, K.Matvienko, D.Maurya, S. K.McKenna, J. A.Mehta, R.Meier, F.Merola, M.Metzner, F.Milesi, M.Miller, C.Mirra, M.Miyabayashi, K.Miyake, H.Mizuk, R.Mohanty, G. B.Molina-Gonzalez, N.Mondal, S.Moneta, S.Moser, H. -G.Mrvar, M.Mussa, R.Nakamura, I.Nakao, M.Nakazawa, Y.Charan, A. NarimaniNaruki, M.Narwal, D.Natkaniec, Z.Natochii, A.Nayak, L.Nayak, M.Nazaryan, G.Niebuhr, C.Nishida, S.Ogawa, S.Ono, H.Onuki, Y.Oskin, P.Otani, F.Pakhlov, P.Pakhlova, G.Panta, A.Pardi, S.Park, H.Park, S. -H.Paschen, B.Passeri, A.Patra, S.Paul, S.Pedlar, T. K.Peschke, R.Pestotnik, R.Piccolo, M.Piilonen, L. E.Podesta-Lerma, P. L. M.Podobnik, T.Pokharel, S.Praz, C.Prell, S.Prencipe, E.Prim, M. T.Purwar, H.Rados, P.Raeuber, G.Raiz, S.Rauls, N.Reif, M.Reiter, S.Ripp-Baudot, I.Rizzo, G.Robertson, S. H.Rocchetti, P.Roehrken, M.Roney, J. M.Rostomyan, A.Rout, N.Russo, G.Sakai, Y.Sanders, D. A.Sandilya, S.Santelj, L.Sato, Y.Savinov, V.Scavino, B.Schmitt, C.Schwanda, C.Seino, Y.Selce, A.Senyo, K.Serrano, J.Sevior, M. E.Sfienti, C.Shan, W.Shen, C. P.Shi, X. D.Shillington, T.Shimasaki, T.Shiu, J. -G.Shtol, D.Sibidanov, A.Simon, F.Singh, J. B.Skorupa, J.Sobie, R. J.Sobotzik, M.Soffer, A.Sokolov, A.Solovieva, E.Spataro, S.Spruck, B.Starič, M.Stavroulakis, P.Stefkova, S.Stroili, R.Sumihama, M.Sumisawa, K.Svidras, H.Takizawa, M.Tamponi, U.Tanaka, S.Tanida, K.Tenchini, F.Tittel, O.Tiwary, R.Tonelli, D.Torassa, E.Trabelsi, K.Tsaklidis, I.Uchida, M.Ueda, I.Uematsu, Y.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.Volpe, R.Wach, B.Wakai, M.Wallner, S.Wang, M. -Z.Wang, X. L.Wang, Z.Warburton, A.Watanuki, S.Wessel, C.Won, E.Xu, X. P.Yabsley, B. D.Yamada, S.Yang, S. B.Yelton, J.Yin, J. H.Yoshihara, K.Yuan, C. Z.Zhang, B.Zhang, Y.Zhilich, V.Zhou, Q. D.Zhou, X. Y.Zhukova, V. I.
Source
Subject
High Energy Physics - Experiment
Language
Abstract
We measure the tau-to-light-lepton ratio of inclusive $B$-meson branching fractions $R(X_{\tau/\ell}) \equiv \mathcal{B}(B\to X \tau \nu)/\mathcal{B}(B \to X \ell \nu)$, where $\ell$ indicates an electron or muon, and thereby test the universality of charged-current weak interactions. We select events that have one fully reconstructed $B$ meson and a charged lepton candidate from $189~\mathrm{fb}^{-1}$ of electron-positron collision data collected with the Belle II detector. We find $R(X_{\tau/\ell}) = 0.228 \pm 0.016~(\mathrm{stat}) \pm 0.036~(\mathrm{syst})$, in agreement with standard-model expectations. This is the first direct measurement of $R(X_{\tau/\ell})$.