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arXiv · 2212.04128

Search for the lepton flavour violating decays $B^{+} \to K^{+} \tau^\pm \ell^\mp$ ($\ell = e, \mu$) at Belle

Belle Collaboration·S. Watanuki·G. de Marino·K. Trabelsi·I. Adachi·H. Aihara·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·Sw. Banerjee·M. Bauer·P. Behera·K. Belous·M. Bessner·V. Bhardwaj·B. Bhuyan·D. Biswas·D. Bodrov·G. Bonvicini·J. Borah·A. Bozek·M. Bračko·P. Branchini·T. E. Browder·A. Budano·M. Campajola·L. Cao·D. Červenkov·M. -C. Chang·B. G. Cheon·K. Chilikin·K. Cho·S. -J. Cho·S. -K. Choi·Y. Choi·S. Choudhury·D. Cinabro·S. Das·G. De Nardo·G. De Pietro·R. Dhamija·F. Di Capua·T. V. Dong·D. Epifanov·T. Ferber·D. Ferlewicz·B. G. Fulsom·R. Garg·V. Gaur·A. Garmash·A. Giri·P. Goldenzweig·E. Graziani·T. Gu·Y. Guan·K. Gudkova·C. Hadjivasiliou·S. Halder·X. Han·T. Hara·K. Hayasaka·H. Hayashii·D. Herrmann·W. -S. Hou·C. -L. Hsu·K. Inami·G. Inguglia·N. Ipsita·A. Ishikawa·R. Itoh·M. Iwasaki·W. W. Jacobs·Q. P. Ji·S. Jia·Y. Jin·K. K. Joo·A. B. Kaliyar·H. Kichimi·C. H. Kim·D. Y. Kim·K. -H. Kim·Y. -K. Kim·K. Kinoshita·P. Kodyš·A. Korobov·S. Korpar·E. Kovalenko·P. Križan·P. Krokovny·T. Kuhr·M. Kumar·K. Kumara·A. Kuzmin·Y. -J. Kwon·J. S. Lange·M. Laurenza·S. C. Lee
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Abstract

We present a search for the lepton-flavour-violating decays $B^+ \to K^+ \tau^\pm \ell^\mp$, with $\ell = (e, \mu)$, using the full data sample of $772 \times 10^6$ $B\overline{B}$ pairs recorded by the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We use events in which one $B$ meson is fully reconstructed in a hadronic decay mode. We find no evidence for $B^\pm \to K^\pm \tau \ell$ decays and set upper limits on their branching fractions at the 90% confidence level in the $(1$-$3) \times 10^{-5}$ range. The obtained limits are the world's best results.

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Belle Collaboration, S. Watanuki, G. de Marino, K. Trabelsi, I. Adachi, H. Aihara, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, Sw. Banerjee, M. Bauer, P. Behera, K. Belous, M. Bessner, V. Bhardwaj, B. Bhuyan, D. Biswas, D. Bodrov, G. Bonvicini, J. Borah, A. Bozek, M. Bračko, P. Branchini, T. E. Browder, A. Budano, M. Campajola, L. Cao, D. Červenkov, M. -C. Chang, B. G. Cheon, K. Chilikin, K. Cho, S. -J. Cho, S. -K. Choi, Y. Choi, S. Choudhury, D. Cinabro, S. Das, G. De Nardo, G. De Pietro, R. Dhamija, F. Di Capua, T. V. Dong, D. Epifanov, T. Ferber, D. Ferlewicz, B. G. Fulsom, R. Garg, V. Gaur, A. Garmash, A. Giri, P. Goldenzweig, E. Graziani, T. Gu, Y. Guan, K. Gudkova, C. Hadjivasiliou, S. Halder, X. Han, T. Hara, K. Hayasaka, H. Hayashii, D. Herrmann, W. -S. Hou, C. -L. Hsu, K. Inami, G. Inguglia, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, W. W. Jacobs, Q. P. Ji, S. Jia, Y. Jin, K. K. Joo, A. B. Kaliyar, H. Kichimi, C. H. Kim, D. Y. Kim, K. -H. Kim, Y. -K. Kim, K. Kinoshita, P. Kodyš, A. Korobov, S. Korpar, E. Kovalenko, P. Križan, P. Krokovny, T. Kuhr, M. Kumar, K. Kumara, A. Kuzmin, Y. -J. Kwon, J. S. Lange, M. Laurenza, S. C. Lee. 2022-12-08. Search for the lepton flavour violating decays $B^{+} \to K^{+} \tau^\pm \ell^\mp$ ($\ell = e, \mu$) at Belle. https://doi.org/10.1103/physrevlett.130.261802

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