Measurement of the time-integrated CP asymmetry in $D^0\to K_S^0 K_S^0$ decays using opposite-side flavor tagging at Belle and Belle II

Abstract We measure the time-integrated CP asymmetry in $D^0\to K_S^0K_S^0$ decays reconstructed in $e^+e^-\to c\bar{c}$ events collected by the Belle and Belle~II experiments. The corresponding data samples have integrated luminosities of 980 and 428\invfb, respectively. To infer the flavor of the $D^0$ meson, we exploit the correlation between the flavor of the reconstructed decay and the electric charges of particles reconstructed in the rest of the $e^+e^-\to c\bar{c}$ event. This results in a sample which is independent from any other previously used at Belle or Belle~II for CP asymmetry measurements. The result, $A_{\rm CP}(D^0\to K_S^0K_S^0) = (1.3\pm 2.0\pm 0.2)\%$, where the first uncertainty is statistical and the second systematic, is consistent with previous determinations and with CP symmetry.
Tags Belle Run 1
Working group Charm
Principal authors @  Michel Bertemes, Angelo Di Canto, Riccardo Manfredi
Reference Phys.Rev.D 112, 012017 (2025), DOI: 10.1103/8x1h-39dp
Document BELLE2-PUB-PH-2025-006
Links arXiv:2504.15881, Inspire, PRD
Bibtex 
@article{Belle:2025cub,
    author = "Adachi, I. and others",
    collaboration = "Belle, Belle-II",
    title = "{Measurement of the time-integrated CP asymmetry in D0{\textrightarrow}KS0KS0 decays using opposite-side flavor tagging at Belle and Belle II}",
    eprint = "2504.15881",
    archivePrefix = "arXiv",
    primaryClass = "hep-ex",
    reportNumber = "Belle II Preprint 2025-006, KEK Preprint 2025-4",
    doi = "10.1103/8x1h-39dp",
    journal = "Phys. Rev. D",
    volume = "112",
    number = "1",
    pages = "012017",
    year = "2025"
}