Search for Bs0→ ℓ∓τ± with the semi-leptonic tagging method at Belle

• Published in: The journal of high energy physics 2023-09, Vol.2023 (8), p.178
• Main Authors: Giri, A., Atmacan, H., Aushev, T., Babu, V., Behera, P., Belous, K., Bennett, J., Bračko, M., Branchini, P., Browder, T. E., Budano, A., Campajola, M., Červenkov, D., Chang, M.-C., Choudhury, S., Cinabro, D., Cochran, J., Das, S., Dash, N., Dong, T. V., Dubey, S., Ferlewicz, D., Garg, R., Gaur, V., Goldenzweig, P., Guan, Y., Hedges, M. T., Hou, W.-S., Hsu, C.-L., Iijima, T., Inami, K., Itoh, R., Iwasaki, M., Jacobs, W. W., Jang, E.-J., Jia, S., Jin, Y., Kaliyar, A. B., Kim, C. H., Konno, T., Korpar, S., Kovalenko, E., Krokovny, P., Kuhr, T., Kumara, K., Kuzmin, A., Kwon, Y.-J., Li, J., Li, Y., Libby, J., Lieret, K., Liventsev, D., Luo, T., Masuda, M., Maurya, S. K., Meier, F., Metzner, F., Miyabayashi, K., Nakao, M., Natkaniec, Z., Natochii, A., Nisar, N. K., Ono, H., Pakhlov, P., Pang, T., Pardi, S., Park, J., Passeri, A., Paul, S., Pedlar, T. K., Prencipe, E., Prim, M. T., Rostomyan, A., Rout, N., Sandilya, S., Sangal, A., Schwanda, C., Seino, Y., Sevior, M. E., Shiu, J.-G., Sibidanov, A., Solovieva, E., Sumiyoshi, T., Takizawa, M., Tanida, K., Tenchini, F., Trabelsi, K., Uchida, M., Unno, Y., Urquijo, P., Vahsen, S. E., Varner, G., Vinokurova, A., Wang, M.-Z., Yan, W., Yelton, J., Yuan, C. Z., Yusa, Y., Zhai, Y., Zhang, Z. P.
• Format: Article
• Language: English
• Subjects: Classical and Quantum Gravitation; Confidence intervals; Decay rate; Elementary Particles; High energy physics; Leptons; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Experimental Physics; Relativity Theory; Sensors; String Theory
• ISSN: 1029-8479
• DOI: 10.1007/JHEP08(2023)178

A bstract We present a search for the lepton-flavor-violating decays B s 0 → ℓ ∓ τ ± , where ℓ = e, μ , using the full data sample of 121 fb − 1 collected at the Υ(5 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. We use B s 0 B ¯ s 0 events in which one B s 0 meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for B s 0 → ℓ ∓ τ ± decays and set upper limits on their branching fractions at 90% confidence level as B ( B s 0 → e ∓ τ ± ) < 14 × 10 − 4 and B ( B s 0 → μ ∓ τ ± ) < 7 . 3 × 10 − 4 . Our result represents the first upper limit on the B s 0 → e ∓ τ ± decay rate.