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Measurement of the $C P$ asymmetry in $D^{0} \to π^{+} π^{-} π^{0}$ decays at Belle II

M. Abumusabh , I. Adachi , L. Aggarwal , H. Ahmed , Y. Ahn , H. Aihara , N. Akopov , S. Alghamdi , M. Alhakami et al. (Belle II Collaboration)

M. Alhakami , A. Aloisio , N. Althubiti , K. Amos , N. Anh Ky , D. M. Asner , H. Atmacan , T. Aushev , R. Ayad , V. Babu , H. Bae , N. K. Baghel , S. Bahinipati , P. Bambade , Sw. Banerjee , M. Barrett , M. Bartl , J. Baudot , A. Beaubien , F. Becherer , J. Becker , J. V. Bennett , F. U. Bernlochner , V. Bertacchi , M. Bertemes , E. Bertholet , M. Bessner , S. Bettarini , V. Bhardwaj , B. Bhuyan , F. Bianchi , T. Bilka , D. Biswas , A. Bobrov , D. Bodrov , G. Bonvicini , J. Borah , A. Boschetti , A. Bozek , M. Bračko , P. Branchini , R. A. Briere , T. E. Browder , A. Budano , S. Bussino , Q. Campagna , M. Campajola , G. Casarosa , C. Cecchi , P. Chang , P. Cheema , L. Chen , B. G. Cheon , C. Cheshta , H. Chetri , K. Chilikin , J. Chin , K. Chirapatpimol , H.-E. Cho , K. Cho , S.-J. Cho , S.-K. Choi , S. Choudhury , J. A. Colorado-Caicedo , I. Consigny , L. Corona , J. X. Cui , S. Das , E. De La Cruz-Burelo , S. A. De La Motte , G. De Nardo , G. De Pietro , R. de Sangro , M. Destefanis , A. Di Canto , Z. Doležal , I. Domínguez Jiménez , T. V. Dong , X. Dong , M. Dorigo , G. Dujany , P. Ecker , D. Epifanov , J. Eppelt , R. Farkas , P. Feichtinger , T. Ferber , T. Fillinger , C. Finck , G. Finocchiaro , F. Forti , B. G. Fulsom , A. Gabrielli , A. Gale , E. Ganiev , M. Garcia-Hernandez , R. Garg , L. Gärtner , G. Gaudino , V. Gaur , V. Gautam , A. Gaz , A. Gellrich , G. Ghevondyan , D. Ghosh , H. Ghumaryan , G. Giakoustidis , R. Giordano , A. Giri , P. Gironella Gironell , A. Glazov , B. Gobbo , R. Godang , O. Gogota , P. Goldenzweig , W. Gradl , E. Graziani , D. Greenwald , Y. Guan , K. Gudkova , I. Haide , Y. Han , H. Hayashii , S. Hazra , M. T. Hedges , A. Heidelbach , G. Heine , I. Heredia de la Cruz , M. Hernández Villanueva , T. Higuchi , M. Hoek , M. Hohmann , R. Hoppe , P. Horak , X. T. Hou , C.-L. Hsu , T. Humair , T. Iijima , N. Ipsita , A. Ishikawa , R. Itoh , M. Iwasaki , P. Jackson , W. W. Jacobs , D. E. Jaffe , E.-J. Jang , S. Jia , Y. Jin , A. Johnson , A. B. Kaliyar , J. Kandra , K. H. Kang , G. Karyan , F. Keil , C. Ketter , C. Kiesling , D. Y. Kim , J.-Y. Kim , K.-H. Kim , H. Kindo , K. Kinoshita , P. Kodyš , T. Koga , S. Kohani , K. Kojima , A. Korobov , S. Korpar , E. Kovalenko , R. Kowalewski , P. Križan , P. Krokovny , T. Kuhr , Y. Kulii , D. Kumar , K. Kumara , T. Kunigo , A. Kuzmin , Y.-J. Kwon , S. Lacaprara , T. Lam , L. Lanceri , J. S. Lange , T. S. Lau , M. Laurenza , R. Leboucher , F. R. Le Diberder , H. Lee , M. J. Lee , C. Lemettais , P. Leo , P. M. Lewis , C. Li , H.-J. Li , L. K. Li , Q. M. Li , W. Z. Li , Y. Li , Y. B. Li , Y. P. Liao , J. Libby , J. Lin , S. Lin , Z. Liptak , V. Lisovskyi , M. H. Liu , Q. Y. Liu , Z. Liu , D. Liventsev , S. Longo , T. Lueck , C. Lyu , J. L. Ma , Y. Ma , M. Maggiora , S. P. Maharana , R. Maiti , G. Mancinelli , R. Manfredi , E. Manoni , M. Mantovano , D. Marcantonio , C. Marinas , C. Martellini , A. Martens , T. Martinov , L. Massaccesi , M. Masuda , D. Matvienko , S. K. Maurya , M. Maushart , J. A. McKenna , Z. Mediankin Gruberová , R. Mehta , F. Meier , D. Meleshko , M. Merola , C. Miller , M. Mirra , K. Miyabayashi , H. Miyake , R. Mizuk , G. B. Mohanty , S. Moneta , A. L. Moreira de Carvalho , H.-G. Moser , M. Mrvar , H. Murakami , R. Mussa , I. Nakamura , M. Nakao , Y. Nakazawa , M. Naruki , Z. Natkaniec , A. Natochii , M. Nayak , M. Neu , S. Nishida , R. Nomaru , S. Ogawa , R. Okubo , H. Ono , E. R. Oxford , G. Pakhlova , A. Panta , S. Pardi , J. Park , S.-H. Park , A. Passeri , S. Patra , S. Paul , T. K. Pedlar , R. Pestotnik , M. Piccolo , L. E. Piilonen , P. L. M. Podesta-Lerma , T. Podobnik , C. Praz , S. Prell , E. Prencipe , M. T. Prim , S. Privalov , H. Purwar , P. Rados , S. Raiz , K. Ravindran , J. U. Rehman , M. Reif , S. Reiter , L. Reuter , D. Ricalde Herrmann , I. Ripp-Baudot , G. Rizzo , S. H. Robertson , J. M. Roney , A. Rostomyan , N. Rout , S. Saha , L. Salutari , D. A. Sanders , S. Sandilya , L. Santelj , C. Santos , V. Savinov , B. Scavino , C. Schmitt , S. Schneider , M. Schnepf , K. Schoenning , C. Schwanda , A. J. Schwartz , Y. Seino , K. Senyo , M. E. Sevior , C. Sfienti , W. Shan , G. Sharma , X. D. Shi , T. Shillington , T. Shimasaki , J.-G. Shiu , D. Shtol , B. Shwartz , A. Sibidanov , F. Simon , J. Skorupa , M. Sobotzik , A. Soffer , A. Sokolov , E. Solovieva , S. Spataro , B. Spruck , M. Starič , P. Stavroulakis , S. Stefkova , L. Stoetzer , R. Stroili , M. Sumihama , K. Sumisawa , H. Svidras , M. Takahashi , M. Takizawa , U. Tamponi , S. Tanaka , K. Tanida , F. Tenchini , A. Thaller , T. Tien Manh , O. Tittel , R. Tiwary , E. Torassa , K. Trabelsi , F. F. Trantou , I. Tsaklidis , I. Ueda , K. Unger , Y. Unno , K. Uno , S. Uno , P. Urquijo , Y. Ushiroda , S. E. Vahsen , R. van Tonder , K. E. Varvell , M. Veronesi , V. S. Vismaya , L. Vitale , V. Vobbilisetti , R. Volpe , M. Wakai , S. Wallner , M.-Z. Wang , A. Warburton , S. Watanuki , C. Wessel , E. Won , X. P. Xu , B. D. Yabsley , W. Yan , J. Yelton , K. Yi , J. H. Yin , K. Yoshihara , C. Z. Yuan , J. Yuan , Y. Yusa , L. Zani , F. Zeng , M. Zeyrek , B. Zhang , V. Zhilich , J. S. Zhou , Q. D. Zhou , L. Zhu , and R. Žlebčík (Belle II Collaboration)

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Phys. Rev. D 113, 052006 – Published 16 March, 2026

DOI: https://doi.org/10.1103/4yv7-1h85

Abstract

We measure the time- and phase-space-integrated $C P$ asymmetry $A_{C P}$ in $D^{0} \to π^{+} π^{-} π^{0}$ decays reconstructed in $e^{+} e^{-} \to c \bar{c}$ events collected by the Belle II experiment from 2019 to 2022. This sample corresponds to an integrated luminosity of $428 {fb}^{- 1}$ . We require $D^{0}$ mesons to be produced in $D^{* +} \to D^{0} π^{+}$ decays to determine their flavor at production. Control samples of $D^{0} \to K^{-} π^{+}$ decays are used to correct for reconstruction-induced asymmetries. The result, $A_{C P} (D^{0} \to π^{+} π^{-} π^{0}) = (0.29 \pm 0.27 \pm 0.13) %$ , where the first uncertainty is statistical and the second systematic, is the most precise result to date and is consistent with $C P$ conservation.

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References (38)

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Phys. Rev. D 113, 052006– Published 16 March, 2026

Vol. 113, Iss. 5 — 1 March 2026

Received 28 October 2025
Accepted 2 February 2026

DOI: https://doi.org/10.1103/4yv7-1h85

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society

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Measurement of the $C P$ asymmetry in $D^{0} \to π^{+} π^{-} π^{0}$ decays at Belle II

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Measurement of the CP asymmetry in D0→π+π−π0 decays at Belle II

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Measurement of the $C P$ asymmetry in $D^{0} \to π^{+} π^{-} π^{0}$ decays at Belle II