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arXiv · 2305.07555

Measurement of $C\!P$ violation in $B^{0}\rightarrow K_{S}^{0}\pi^{0}$ decays at Belle II

Belle II Collaboration·I. Adachi·K. Adamczyk·L. Aggarwal·H. Ahmed·H. Aihara·N. Akopov·A. Aloisio·N. Anh Ky·D. M. Asner·H. Atmacan·T. Aushev·V. Aushev·M. Aversano·V. Babu·H. Bae·S. Bahinipati·P. Bambade·Sw. Banerjee·M. Barrett·J. Baudot·M. Bauer·A. Baur·A. Beaubien·J. Becker·P. K. Behera·J. V. Bennett·V. Bertacchi·M. Bertemes·E. Bertholet·M. Bessner·S. Bettarini·B. Bhuyan·F. Bianchi·T. Bilka·D. Biswas·D. Bodrov·A. Bondar·J. Borah·A. Bozek·M. Bračko·P. Branchini·R. A. Briere·T. E. Browder·A. Budano·S. Bussino·M. Campajola·L. Cao·G. Casarosa·C. Cecchi·J. Cerasoli·P. Chang·R. Cheaib·P. Cheema·V. Chekelian·C. Chen·B. G. Cheon·K. Chilikin·K. Chirapatpimol·H. -E. Cho·K. Cho·S. -J. Cho·S. -K. Choi·S. Choudhury·J. Cochran·L. Corona·L. M. Cremaldi·S. Das·F. Dattola·E. De La Cruz-Burelo·S. A. De La Motte·G. de Marino·M. De Nuccio·G. De Pietro·R. de Sangro·M. Destefanis·A. De Yta-Hernandez·R. Dhamija·A. Di Canto·F. Di Capua·J. Dingfelder·Z. Doležal·I. Domínguez Jiménez·T. V. Dong·M. Dorigo·K. Dort·S. Dreyer·S. Dubey·G. Dujany·P. Ecker·M. Eliachevitch·P. Feichtinger·T. Ferber·D. Ferlewicz·T. Fillinger·C. Finck·G. Finocchiaro·A. Fodor·F. Forti·B. G. Fulsom
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Abstract

We report a measurement of the $C\!P$-violating parameters $A$ and $S$ in $B^{0}\to K_{S}^{0} \pi^{0}$ decays at Belle II using a sample of $387\times 10^{6}$ $B\bar{B}$ events recorded in $e^{+}e^{-}$ collisions at a center-of-mass energy corresponding to the $\Upsilon(4S)$ resonance. These parameters are determined by fitting the proper decay-time distribution of a sample of 415 signal events. We obtain $A = 0.04^{+0.15}_{-0.14}\pm 0.05$ and $S = 0.75^{+0.20}_{-0.23}\pm 0.04$, where the first uncertainties are statistical and the second are systematic.

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Belle II Collaboration, I. Adachi, K. Adamczyk, L. Aggarwal, H. Ahmed, H. Aihara, N. Akopov, A. Aloisio, N. Anh Ky, D. M. Asner, H. Atmacan, T. Aushev, V. Aushev, M. Aversano, V. Babu, H. Bae, S. Bahinipati, P. Bambade, Sw. Banerjee, M. Barrett, J. Baudot, M. Bauer, A. Baur, A. Beaubien, J. Becker, P. K. Behera, J. V. Bennett, V. Bertacchi, M. Bertemes, E. Bertholet, M. Bessner, S. Bettarini, B. Bhuyan, F. Bianchi, T. Bilka, D. Biswas, D. Bodrov, A. Bondar, J. Borah, A. Bozek, M. Bračko, P. Branchini, R. A. Briere, T. E. Browder, A. Budano, S. Bussino, M. Campajola, L. Cao, G. Casarosa, C. Cecchi, J. Cerasoli, P. Chang, R. Cheaib, P. Cheema, V. Chekelian, C. Chen, B. G. Cheon, K. Chilikin, K. Chirapatpimol, H. -E. Cho, K. Cho, S. -J. Cho, S. -K. Choi, S. Choudhury, J. Cochran, L. Corona, L. M. Cremaldi, S. Das, F. Dattola, E. De La Cruz-Burelo, S. A. De La Motte, G. de Marino, M. De Nuccio, G. De Pietro, R. de Sangro, M. Destefanis, A. De Yta-Hernandez, R. Dhamija, A. Di Canto, F. Di Capua, J. Dingfelder, Z. Doležal, I. Domínguez Jiménez, T. V. Dong, M. Dorigo, K. Dort, S. Dreyer, S. Dubey, G. Dujany, P. Ecker, M. Eliachevitch, P. Feichtinger, T. Ferber, D. Ferlewicz, T. Fillinger, C. Finck, G. Finocchiaro, A. Fodor, F. Forti, B. G. Fulsom. 2023-05-12. Measurement of $C\!P$ violation in $B^{0}\rightarrow K_{S}^{0}\pi^{0}$ decays at Belle II. https://doi.org/10.1103/physrevlett.131.111803

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