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arXiv · 2301.10989

Search for $B{}^0_s \rightarrow \ell^{\mp} \tau^{\pm}$ with the Semi-leptonic Tagging Method at Belle

Belle Collaboration·L. Nayak·S. Nishida·A. Giri·I. Adachi·H. Aihara·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·S. Bahinipati·Sw. Banerjee·M. Bauer·P. Behera·K. Belous·J. Bennett·M. Bessner·B. Bhuyan·D. Biswas·D. Bodrov·J. Borah·A. Bozek·M. Bračko·P. Branchini·T. E. Browder·A. Budano·M. Campajola·D. Červenkov·M. -C. Chang·B. G. Cheon·K. Chilikin·H. E. Cho·K. Cho·S. -K. Choi·Y. Choi·S. Choudhury·D. Cinabro·J. Cochran·S. Das·N. Dash·G. De Nardo·G. De Pietro·R. Dhamija·F. Di Capua·J. Dingfelder·Z. Doležal·T. V. Dong·D. Dossett·S. Dubey·D. Epifanov·T. Ferber·D. Ferlewicz·B. G. Fulsom·R. Garg·V. Gaur·P. Goldenzweig·E. Graziani·T. Gu·Y. Guan·S. Halder·T. Hara·K. Hayasaka·H. Hayashii·M. T. Hedges·D. Herrmann·W. -S. Hou·C. -L. Hsu·T. Iijima·K. Inami·G. Inguglia·N. Ipsita·A. Ishikawa·R. Itoh·M. Iwasaki·W. W. Jacobs·E. -J. Jang·S. Jia·Y. Jin·K. K. Joo·A. B. Kaliyar·T. Kawasaki·C. Kiesling·C. H. Kim·D. Y. Kim·K. -H. Kim·Y. -K. Kim·K. Kinoshita·P. Kodyš·T. Konno·A. Korobov·S. Korpar·E. Kovalenko·P. Križan·P. Krokovny·T. Kuhr·M. Kumar·R. Kumar·K. Kumara
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Abstract

We present a search for the lepton-flavor-violating decays $B{}^0_s \rightarrow \ell^{\mp}\tau^{\pm}$, where $\ell = e, \mu$, using the full data sample of $121~\mathrm{fb}^{-1}$ collected at the $\Upsilon(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We use $B{}^0_s \overline{B}{}^0_s$ events in which one $B{}^0_s$ meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for $B{}^0_s \rightarrow \ell^{\mp}\tau^{\pm}$ decays and set upper limits on their branching fractions at $90\%$ confidence level as $\mathcal{B}(B{}^0_s \rightarrow e^{\mp}\tau^{\pm}) < 14 \times 10^{-4}$ and $\mathcal{B}(B{}^0_s \rightarrow \mu^{\mp}\tau^{\pm}) < 7.3 \times 10^{-4}$. Our result represents the first upper limit on the $B{}^0_s \rightarrow e^{\mp}\tau^{\pm}$ decay rate.

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Belle Collaboration, L. Nayak, S. Nishida, A. Giri, I. Adachi, H. Aihara, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, Sw. Banerjee, M. Bauer, P. Behera, K. Belous, J. Bennett, M. Bessner, B. Bhuyan, D. Biswas, D. Bodrov, J. Borah, A. Bozek, M. Bračko, P. Branchini, T. E. Browder, A. Budano, M. Campajola, D. Červenkov, M. -C. Chang, B. G. Cheon, K. Chilikin, H. E. Cho, K. Cho, S. -K. Choi, Y. Choi, S. Choudhury, D. Cinabro, J. Cochran, S. Das, N. Dash, G. De Nardo, G. De Pietro, R. Dhamija, F. Di Capua, J. Dingfelder, Z. Doležal, T. V. Dong, D. Dossett, S. Dubey, D. Epifanov, T. Ferber, D. Ferlewicz, B. G. Fulsom, R. Garg, V. Gaur, P. Goldenzweig, E. Graziani, T. Gu, Y. Guan, S. Halder, T. Hara, K. Hayasaka, H. Hayashii, M. T. Hedges, D. Herrmann, W. -S. Hou, C. -L. Hsu, T. Iijima, K. Inami, G. Inguglia, N. Ipsita, A. Ishikawa, R. Itoh, M. Iwasaki, W. W. Jacobs, E. -J. Jang, S. Jia, Y. Jin, K. K. Joo, A. B. Kaliyar, T. Kawasaki, C. Kiesling, C. H. Kim, D. Y. Kim, K. -H. Kim, Y. -K. Kim, K. Kinoshita, P. Kodyš, T. Konno, A. Korobov, S. Korpar, E. Kovalenko, P. Križan, P. Krokovny, T. Kuhr, M. Kumar, R. Kumar, K. Kumara. 2023-01-26. Search for $B{}^0_s \rightarrow \ell^{\mp} \tau^{\pm}$ with the Semi-leptonic Tagging Method at Belle. https://doi.org/10.1007/jhep08(2023)178

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