Measurement of the CP asymmetry in $D^0\to\pi^+\pi^-\pi^0$ decays at Belle II

Sumitted to PubDB: 2025-06-20

Category: Physics / performance paper

Tags: Run 1

Principal Authors Giulia Casarosa, Ludovico Massaccesi
Date 2026-03-17
Working group Charm
Belle II Number BELLE2-PUB-PH-2025-022
Abstract KEK-PREPRINT-2025-17 We measure the time- and phase-space-integrated $C\!P$ asymmetry $A_{C\!P}$ in $D^0\to\pi^+\pi^-\pi^0$ 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 flavor-conserving $D^{*+}\to D^0\pi^+$ decays to determine their flavor at production. Control samples of $D^0\to K^-\pi^+$ decays are used to correct for reconstruction-induced asymmetries. The result, $A_{C\!P}(D^0\to\pi^+\pi^-\pi^0)=(0.29\pm0.27\pm0.13)\%$, where the first uncertainty is statistical and the second systematic, is consistent with conservation of $C\!P$ symmetry and is the most precise determination to date.
Link to LaTeX code https://gitlab.desy.de/ludovico.massaccesi/acp-d023pi-paper
ArXiv https://arxiv.org/abs/2510.21224
Inspire https://inspirehep.net/literature/3072959
DOI https://doi.org/10.1103/4yv7-1h85
Bibtex 
@article{Belle-II:2025zqj,
    author = "Abumusabh, M. and others",
    collaboration = "Belle-II",
    title = "{Measurement of the $CP$ asymmetry in $D^0\toπ^+π^-π^0$ decays at Belle II}",
    eprint = "2510.21224",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II preprint 2025-018, KEK preprint 2025-17",
    month = "10",
    year = "2025"
}
Journal Phys.Rev.D
Preprint Number 2025-018

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