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

2025/10/24 by Belle II Collaboration, Abumusabh, M., Adachi, I. +400
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2510.21224

Abstract

We measure the time- and phase-space-integrated CP asymmetry A_CP in D⁰→π⁺π^-π⁰ decays reconstructed in e⁺e^-→ c 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 D⁰ mesons to be produced in D^*+→ D⁰π⁺ decays to determine their flavor at production. Control samples of D⁰→ K^-π⁺ decays are used to correct for reconstruction-induced asymmetries. The result, A_CP(D⁰→π⁺π^-π⁰)=(0.29±0.27±0.13)%, where the first uncertainty is statistical and the second systematic, is the most precise result to date and is consistent with CP conservation.

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