Measurement of the time-integrated CP asymmetry in D⁰→π⁰π⁰ decays at Belle II

2025/05/05 by Belle II Collaboration, Adachi, I., Ahn, Y. +372
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)

paper · doi:10.48550/arxiv.2505.02912

Abstract

We measure the time-integrated CP asymmetry, A_CP, in D⁰→π⁰π⁰ decays reconstructed in e⁺e^-→ cc events collected by Belle II during 2019--2022. The data corresponds to an integrated luminosity of 428fb^-1. The D⁰ decays are required to originate from the flavor-conserving D^*+ → D⁰ π⁺ decay to determine the charm flavor at production time. Control samples of D⁰→ K^- π⁺ decays, with or without an associated pion from a D^*+ decay, are used to correct for detection asymmetries. The result, A_CP(D⁰→π⁰π⁰) = (0.30± 0.72± 0.20)%, where the first uncertainty is statistical and the second systematic, is consistent with CP symmetry.

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