Observation of time-dependent $CP$ violation and measurement of the branching fraction of $B^0 \to J/\psi \pi^0$ decays
Creators: name: Adachi, I.
name: Aggarwal, L.
name: Ahmed, H.
name: Aihara, H.
name: Akopov, N.
name: Aloisio, A.
name: Althubiti, N.
name: Anh Ky, N.
name: Asner, D. M.
name: Atmacan, H.
name: Aushev, V.
name: Aversano, M.
name: Ayad, R.
name: Babu, V.
name: Bae, H.
name: Baghel, N. K.
name: Bahinipati, S.
name: Bambade, P.
name: Banerjee, Sw.
name: Bansal, S.
name: Baudot, J.
name: Baur, A.
name: Beaubien, A.
name: Becherer, F.
name: Becker, J.
name: Bennett, J. V.
name: Bernlochner, F. U.
name: Bertacchi, V.
name: Bertemes, M.
name: Bertholet, E.
name: Bessner, M.
name: Bettarini, S.
name: Bhardwaj, V.
name: Bianchi, F.
name: Bilka, T.
name: Biswas, D.
name: Bobrov, A.
name: Bodrov, D.
name: Bondar, A.
name: Borah, J.
name: Boschetti, A.
name: Bozek, A.
name: Bračko, M.
name: Branchini, P.
name: Briere, R. A.
name: Browder, T. E.
name: Budano, A.
name: Bussino, S.
name: Campagna, Q.
name: Campajola, M.
name: Cao, L.
name: Casarosa, G.
name: Cecchi, C.
name: Cerasoli, J.
name: Chang, M.-C.
name: Chang, P.
name: Cheaib, R.
name: Cheema, P.
name: Chen, C.
name: Cheon, B. G.
name: Chilikin, K.
name: Chirapatpimol, K.
name: Cho, H.-E.
name: Cho, K.
name: Cho, S.-J.
name: Choi, S.-K.
name: Choudhury, S.
name: Cochran, J.
name: Corona, L.
name: Cui, J. X.
name: De La Cruz-Burelo, E.
name: De La Motte, S. A.
name: De Nardo, G.
name: De Pietro, G.
name: de Sangro, R.
name: Destefanis, M.
name: Dhamija, R.
name: Di Canto, A.
name: Di Capua, F.
name: Dingfelder, J.
name: Doležal, Z.
name: Dong, T. V.
name: Dorigo, M.
name: Dubey, S.
name: Dugic, K.
name: Dujany, G.
name: Ecker, P.
name: Epifanov, D.
name: Feichtinger, P.
name: Ferber, T.
name: Fillinger, T.
name: Finck, C.
name: Finocchiaro, G.
name: Fodor, A.
name: Forti, F.
name: Fulsom, B. G.
name: Gabrielli, A.
name: Ganiev, E.
name: Garcia-Hernandez, M.
name: Garg, R.
name: Gaudino, G.
name: Gaur, V.
name: Gaz, A.
name: Gellrich, A.
name: Ghevondyan, G.
name: Ghosh, D.
name: Ghumaryan, H.
name: Giakoustidis, G.
name: Giordano, R.
name: Giri, A.
name: Gironella, P.
name: Glazov, A.
name: Gobbo, B.
name: Godang, R.
name: Gogota, O.
name: Goldenzweig, P.
name: Gradl, W.
name: Granderath, S.
name: Graziani, E.
name: Gruberová, Z.
name: Guan, Y.
name: Gudkova, K.
name: Haide, I.
name: Han, Y.
name: Hara, T.
name: Hayashii, H.
name: Hazra, S.
name: Hearty, C.
name: Heidelbach, A.
name: de la Cruz, I. Heredia
name: Hernández Villanueva, M.
name: Higuchi, T.
name: Hoek, M.
name: Hohmann, M.
name: Hoppe, R.
name: Horak, P.
name: Hsu, C.-L.
name: Humair, T.
name: Iijima, T.
name: Inami, K.
name: Ipsita, N.
name: Ishikawa, A.
name: Itoh, R.
name: Iwasaki, M.
name: Jackson, P.
name: Jacobs, W. W.
name: Jang, E.-J.
name: Jia, S.
name: Jin, Y.
name: Johnson, A.
name: Joo, K. K.
name: Junkerkalefeld, H.
name: Kalita, D.
name: Kandra, J.
name: Kang, K. H.
name: Kang, S.
name: Kawasaki, T.
name: Keil, F.
name: Ketter, C.
name: Kiesling, C.
name: Kim, C.-H.
name: Kim, D. Y.
name: Kim, J.-Y.
name: Kim, K.-H.
name: Kim, Y.-K.
name: Kim, Y. J.
name: Kinoshita, K.
name: Kodyš, P.
name: Koga, T.
name: Kohani, S.
name: Kojima, K.
name: Korobov, A.
name: Korpar, S.
name: Kovalenko, E.
name: Kowalewski, R.
name: Križan, P.
name: Krokovny, P.
name: Kuhr, T.
name: Kulii, Y.
name: Kumar, D.
name: Kumar, R.
name: Kumara, K.
name: Kunigo, T.
name: Kuzmin, A.
name: Kwon, Y.-J.
name: Lai, Y.-T.
name: Lalwani, K.
name: Lam, T.
name: Lau, T. S.
name: Laurenza, M.
name: Leboucher, R.
name: Le Diberder, F. R.
name: Lee, M. J.
name: Lemettais, C.
name: Leo, P.
name: Li, L. K.
name: Li, Q. M.
name: Li, W. Z.
name: Li, Y.
name: Li, Y. B.
name: Liao, Y. P.
name: Libby, J.
name: Lin, J.
name: Liu, M. H.
name: Liu, Q. Y.
name: Liu, Y.
name: Liu, Z. Q.
name: Liventsev, D.
name: Longo, S.
name: Lueck, T.
name: Lyu, C.
name: Maggiora, M.
name: Maharana, S. P.
name: Maiti, R.
name: Mancinelli, G.
name: Manfredi, R.
name: Manoni, E.
name: Mantovano, M.
name: Marcantonio, D.
name: Marcello, S.
name: Marinas, C.
name: Martellini, C.
name: Martens, A.
name: Martini, A.
name: Martinov, T.
name: Massaccesi, L.
name: Masuda, M.
name: Maurya, S. K.
name: McKenna, J. A.
name: Mehta, R.
name: Meier, F.
name: Merola, M.
name: Miller, C.
name: Mirra, M.
name: Mitra, S.
name: Miyabayashi, K.
name: Mohanty, G. B.
name: Mondal, S.
name: Moneta, S.
name: Moser, H.-G.
name: Mussa, R.
name: Nakamura, I.
name: Nakao, M.
name: Nakazawa, Y.
name: Naruki, M.
name: Natkaniec, Z.
name: Natochii, A.
name: Nayak, M.
name: Nazaryan, G.
name: Neu, M.
name: Nishida, S.
name: Ogawa, S.
name: Ono, H.
name: Onuki, Y.
name: Otani, F.
name: Pakhlov, P.
name: Pakhlova, G.
name: Paoloni, E.
name: Pardi, S.
name: Park, H.
name: Park, J.
name: Park, K.
name: Park, S.-H.
name: Paschen, B.
name: Passeri, A.
name: Pedlar, T. K.
name: Peruzzi, I.
name: Peschke, R.
name: Pestotnik, R.
name: Piccolo, M.
name: Piilonen, L. E.
name: Podobnik, T.
name: Pokharel, S.
name: Praz, C.
name: Prell, S.
name: Prencipe, E.
name: Prim, M. T.
name: Prudiiev, I.
name: Purwar, H.
name: Rados, P.
name: Raeuber, G.
name: Raiz, S.
name: Rauls, N.
name: Reif, M.
name: Reiter, S.
name: Remnev, M.
name: Reuter, L.
name: Ripp-Baudot, I.
name: Rizzo, G.
name: Roehrken, M.
name: Roney, J. M.
name: Rostomyan, A.
name: Rout, N.
name: Sanders, D. A.
name: Sandilya, S.
name: Santelj, L.
name: Savinov, V.
name: Scavino, B.
name: Schmitt, C.
name: Schneider, S.
name: Schnepf, M.
name: Schoenning, K.
name: Schwanda, C.
name: Schwartz, A. J.
name: Seino, Y.
name: Selce, A.
name: Senyo, K.
name: Serrano, J.
name: Sevior, M. E.
name: Sfienti, C.
name: Shan, W.
name: Sharma, C.
name: Shen, C. P.
name: Shi, X. D.
name: Shillington, T.
name: Shimasaki, T.
name: Shiu, J.-G.
name: Shtol, D.
name: Shwartz, B.
name: Sibidanov, A.
name: Simon, F.
name: Singh, J. B.
name: Skorupa, J.
name: Sobie, R. J.
name: Sobotzik, M.
name: Soffer, A.
name: Sokolov, A.
name: Solovieva, E.
name: Spataro, S.
name: Spruck, B.
name: Song, W.
name: Starič, M.
name: Stavroulakis, P.
name: Stefkova, S.
name: Stroili, R.
name: Strube, J.
name: Sue, Y.
name: Sumihama, M.
name: Sumisawa, K.
name: Sutcliffe, W.
name: Suwonjandee, N.
name: Svidras, H.
name: Takahashi, M.
name: Takizawa, M.
name: Tamponi, U.
name: Tanida, K.
name: Tenchini, F.
name: Thaller, A.
name: Tittel, O.
name: Tiwary, R.
name: Torassa, E.
name: Trabelsi, K.
name: Tsaklidis, I.
name: Uchida, M.
name: Ueda, I.
name: Unger, K.
name: Unno, Y.
name: Uno, K.
name: Uno, S.
name: Urquijo, P.
name: Ushiroda, Y.
name: Vahsen, S. E.
name: van Tonder, R.
name: Veronesi, M.
name: Vismaya, V. S.
name: Vitale, L.
name: Vobbilisetti, V.
name: Volpe, R.
name: Wakai, M.
name: Wallner, S.
name: Wang, M.-Z.
name: Wang, X. L.
name: Wang, Z.
name: Warburton, A.
name: Watanuki, S.
name: Wessel, C.
name: Won, E.
name: Xu, X. P.
name: Yabsley, B. D.
name: Yamada, S.
name: Yan, W.
name: Yelton, J.
name: Yin, J. H.
name: Yoshihara, K.
name: Yusa, Y.
name: Zani, L.
name: Zeng, F.
name: Zhang, B.
name: Zhilich, V.
name: Zhou, J. S.
name: Zhou, Q. D.
name: Zhukova, V. I.
name: Žlebčík, R.
name: Belle-II Collaboration
Publisher: name: Deutsches Elektronen-Synchrotron, DESY, Hamburg
Year: 2024

description: We present a measurement of the branching fraction and time-dependent charge-parity ($CP$) decay-rate asymmetries in $B^0 \to J/\psi \pi^0$ 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\overline{B}$ meson pairs from $\Upsilon(4S)$ decays. We reconstruct $392\pm 24$ signal decays and fit the $CP$ parameters from the distribution of the proper-decay-time difference of the two $B$ mesons. We measure the branching fraction to be $B(B^0 \to J/\psi \pi^0)=(2.02 \pm 0.12 \pm 0.10)\times 10^{-5}$ and the direct and mixing-induced $CP$ asymmetries to be $C_{CP}=0.13 \pm 0.12 \pm 0.03$ and $S_{CP}=-0.88 \pm 0.17 \pm 0.03$, respectively, where the first uncertainties are statistical and the second are systematic. We observe mixing-induced $CP$ violation with a significance of $5.0$ standard deviations for the first time in this mode.