Bodrov, D.Pakhlov, P.Adachi, I.Aihara, H.Al Said, S.Asner, D. M.Atmacan, H.Aushev, T.Ayad, R.Babu, V.Banerjee, SwBehera, P.Belous, K.Bennett, J.Bessner, M.Bhuyan, B.Bilka, T.Biswas, D.Bobrov, A.Bondar, A.Borah, J.Bozek, A.Bracko, M.Branchini, P.Browder, T. E.Budano, A.Campajola, M.Cervenkov, D.Chang, M. -C.Cheon, B. G.Chilikin, K.Cho, H. E.Cho, K.Cho, S. -J.Choi, S. -K.Choi, Y.Choudhury, S.Cinabro, D.Das, S.De Nardo, G.De Pietro, G.Dhamija, R.Di Capua, F.Dingfelder, J.Dolezal, Z.Dong, T. V.Epifanov, D.Ferber, T.Ferlewicz, D.Fulsom, B. G.Gaur, V.Garmash, A.Giri, A.Goldenzweig, P.Graziani, E.Greenwald, D.Gu, T.Guan, Y.Gudkova, K.Hadjivasiliou, C.Halder, S.Hayasaka, K.Hayashii, H.Hedges, M. T.Herrmann, D.Hou, W. -S.Hsu, C. -L.Iijima, T.Inami, K.Ipsita, N.Ishikawa, A.Itoh, R.Iwasaki, M.Jacobs, W. W.Jang, E. -J.Ji, Q. P.Jia, S.Jin, Y.Joo, K. K.Kalita, D.Kaliyar, A. B.Kawasaki, T.Kiesling, C.Kim, C. H.Kim, D. Y.Kim, K. -H.Kim, Y. -K.Kindo, H.Kinoshita, K.Kodys, P.Korpar, S.Krizan, P.Krokovny, P.Kuhr, T.Kumar, M.Kumar, R.Kumara, K.Kwon, Y. -J.Lange, J. S.Lee, S. C.Li, J.Li, L. K.Libby, J.Lieret, K.Lin, Y. -R.Liventsev, D.Luo, T.Ma, Y.Masuda, M.Matsuda, T.Maurya, S. K.Meier, F.Merola, M.Metzner, F.Miyabayashi, K.Mizuk, R.Mohanty, G. B.Mussa, R.Nakao, M.Narwal, D.Natkaniec, Z.Natochii, A.Nayak, L.Nayak, M.Nisar, N. K.Nishida, S.Ogawa, S.Oskin, P.Pakhlova, G.Pardi, S.Park, H.Park, J.Park, S. -H.Passeri, A.Patra, S.Paul, S.Pestotnik, R.Piilonen, Leo E.Podobnik, T.Prencipe, E.Prim, M. T.Rabusov, A.Rout, N.Russo, G.Sandilya, S.Sangal, A.Santelj, L.Savinov, V.Schnell, G.Schwanda, C.Seino, Y.Senyo, K.Shan, W.Shapkin, M.Sharma, C.Shiu, J. -G.Singh, J. B.Sokolov, A.Solovieva, E.Staric, M.Stottler, Z. S.Sumihama, M.Takizawa, M.Tamponi, U.Tanida, K.Tenchini, F.Tiwary, R.Trabelsi, K.Uchida, M.Uglov, T.Unno, Y.Uno, K.Uno, S.Vahsen, S. E.Varner, G.Vinokurova, A.Vossen, A.Wang, D.Wang, E.Wang, M. -Z.Watanuki, S.Werbycka, O.Xu, X.Yabsley, B. D.Yan, W.Yang, S. B.Yelton, J.Yin, J. H.Yuan, C. Z.Yusa, Y.Zhang, Z. P.Zhilich, V.Zhukova, V.2023-12-082023-12-082023-07-112023-07-110031-9007https://hdl.handle.net/10919/117152We report the first measurement of the Michel parameter ζ′ in the τ-→μ-ν¯μντ decay with a new method proposed just recently. The measurement is based on the reconstruction of the τ-→μ-ν¯μντ events with subsequent muon decay in flight in the Belle central drift chamber. The analyzed data sample of 988 fb-1 collected by the Belle detector corresponds to approximately 912×106 τ+τ- pairs. We measure ζ′=0.22±0.94(stat)±0.42(syst), which is in agreement with the standard model prediction of ζ′=1. Statistical uncertainty dominates in this study, being a limiting factor, while systematic uncertainty is well under control. Our analysis proved the practicability of this promising method and its prospects for further precise measurement in future experiments.6 page(s)Printapplication/pdfenIn CopyrightScience & TechnologyPhysical SciencesPhysics, MultidisciplinaryPhysicsBelle Collaboration5106 Nuclear and Plasma Physics5107 Particle and High Energy Physics5110 Synchrotrons and Accelerators51 Physical Sciences40 Engineering49 Mathematical sciencesArticle - Refereedhttps://doi.org/10.1103/PhysRevLett.131.0218011312Piilonen, Leo [0000-0001-6836-0748]375059601079-7114