Observation of time-dependent C P violation and measurement of the branching fraction of B 0 → J / ψ π 0 decays

Adachi, I.; Aggarwal, L.; Ahmed, H.; Aihara, H.; Akopov, N.; Aloisio, A.; Althubiti, N.; Anh Ky, N.; Asner, D. M.; Atmacan, H.; Aushev, V.; Aversano, M.; Ayad, R.; Babu, V.; Bae, H.; Baghel, N. K.; Bahinipati, S.; Bambade, P.; Banerjee, Sw.; Bansal, S.; 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.; Bhardwaj, V.; Bianchi, F.; Bilka, T.; Biswas, D.; Bobrov, A.; Bodrov, D.; Bondar, A.; Borah, J.; Boschetti, A.; Bozek, A.; Bračko, M.; Branchini, P.; Briere, R. A.; Browder, T. E.; Budano, A.; Bussino, S.; Campagna, Q.; Campajola, M.; Cao, L.; Casarosa, G.; Cecchi, C.; Cerasoli, J.; Chang, M. -C.; Chang, P.; Cheaib, R.; Cheema, P.; Chen, C.; Cheon, B. G.; Chilikin, K.; Chirapatpimol, K.; Cho, H. -E.; Cho, K.; Cho, S. -J.; Choi, S. -K.; Choudhury, S.; Cochran, J.; Corona, L.; Cui, J. X.; De La Cruz-Burelo, E.; De La Motte, S. A.; De Nardo, G.; 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.; Dubey, S.; Dugic, K.; Dujany, G.; Ecker, P.; Epifanov, D.; Feichtinger, P.; Ferber, T.; Fillinger, T.; Finck, C.; Finocchiaro, G.; Fodor, A.; Forti, F.; Fulsom, B. G.; Gabrielli, A.; 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.; Gironella, P.; Glazov, A.; Gobbo, B.; Godang, R.; Gogota, O.; Goldenzweig, P.; Gradl, W.; Granderath, S.; Graziani, E.; Gruberová, Z.; Guan, Y.; Gudkova, K.; Haide, I.; Han, Y.; Hara, T.; Hayashii, H.; Hazra, S.; Hearty, C.; Heidelbach, A.; Heredia de la Cruz, I.; Hernández Villanueva, M.; Higuchi, T.; Hoek, M.; Hohmann, M.; Hoppe, R.; Horak, P.; Hsu, C. -L.; Humair, T.; Iijima, T.; Inami, K.; Ipsita, N.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Jackson, P.; Jacobs, W. W.; Jang, E. -J.; Jia, S.; Jin, Y.; Johnson, A.; Joo, K. K.; Junkerkalefeld, H.; Kalita, D.; Kandra, J.; Kang, K. H.; Kang, S.; Kawasaki, T.; Keil, F.; Ketter, C.; Kiesling, C.; Kim, C. -H.; Kim, D. Y.; Kim, J. -Y.; Kim, K. -H.; Kim, Y. -K.; Kim, Y. J.; Kinoshita, K.; Kodyš, P.; Koga, T.; Kohani, S.; Kojima, K.; Korobov, A.; Korpar, S.; Kovalenko, E.; Kowalewski, R.; Križan, P.; Krokovny, P.; Kuhr, T.; Kulii, Y.; Kumar, D.; Kumar, R.; Kumara, K.; Kunigo, T.; Kuzmin, A.; Kwon, Y. -J.; Lai, Y. -T.; Lalwani, K.; Lam, T.; Lau, T. S.; Laurenza, M.; Leboucher, R.; Le Diberder, F. R.; Lee, M. J.; Lemettais, C.; Leo, P.; Li, L. K.; Li, Q. M.; Li, W. Z.; Li, Y.; Li, Y. B.; Liao, Y. P.; Libby, J.; Lin, J.; Liu, M. H.; Liu, Q. Y.; Liu, Y.; Liu, Z. Q.; Liventsev, D.; Longo, S.; Lueck, T.; Lyu, C.; Maggiora, M.; Maharana, S. 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J.; Sobotzik, M.; Soffer, A.; Sokolov, A.; Solovieva, E.; Spataro, S.; Spruck, B.; Song, W.; Starič, M.; Stavroulakis, P.; Stefkova, S.; Stroili, R.; Strube, J.; Sue, Y.; Sumihama, M.; Sumisawa, K.; Sutcliffe, W.; Suwonjandee, N.; Svidras, H.; Takahashi, M.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Thaller, A.; Tittel, O.; Tiwary, R.; Torassa, E.; Trabelsi, K.; Tsaklidis, I.; Uchida, M.; Ueda, I.; Unger, K.; Unno, Y.; Uno, K.; Uno, S.; Urquijo, P.; Ushiroda, Y.; Vahsen, S. E.; van Tonder, R.; Veronesi, M.; Vismaya, V. S.; Vitale, L.; Vobbilisetti, V.; Volpe, R.; 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.; Yan, W.; Yelton, J.; Yin, J. H.; Yoshihara, K.; Yusa, Y.; Zani, L.; Zeng, F.; Zhang, B.; Zhilich, V.; Zhou, J. S.; Zhou, Q. D.; Zhukova, V. I.; Žlebčík, R.

doi:10.1103/PhysRevD.111.012011

Title: Observation of time-dependent $C P$ violation and measurement of the branching fraction of $B^{0} \to J / ψ π^{0}$ decays

Journal Article · 26 January 2025 · Physical Review. D.

DOI: https://doi.org/10.1103/PhysRevD.111.012011 · OSTI ID:2507112

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We present a measurement of the branching fraction and time-dependent charge-parity ( $C P$ ) decay-rate asymmetries in $B^{0} \to J / ψ π^{0}$ decays. The data sample was collected with the Belle II detector at the SuperKEKB asymmetric $e^{+} e^{-}$ collider in 2019–2022 and contains $(387 \pm 6) \times 10^{6} B \bar{B}$ meson pairs from $ϒ (4 S)$ decays. We reconstruct $392 \pm 24$ signal decays and fit the $C P$ parameters from the distribution of the proper-decay-time difference of the two $B$ mesons. We measure the branching fraction to be $(B^{0} \to J / ψ π^{0}) = (2.00 \pm 0.12 \pm 0.09) \times 10^{- 5}$ and the direct and mixing-induced $C P$ asymmetries to be $C_{C P} = 0.13 \pm 0.12 \pm 0.03$ and $S_{C P} = - 0.88 \pm 0.17 \pm 0.03$ , respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced $C P$ violation with a significance of 5.0 standard deviations for the first time in this mode. Published by the American Physical Society 2025

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Sponsoring Organization:: USDOE

Grant/Contract Number:: AC06-76RL01830; AC06-76RL01830

OSTI ID:: 2507112

Journal Information:: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 1 Vol. 111; ISSN PRVDAQ; ISSN 2470-0010

Publisher:: American Physical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

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