JHEP 2024, (2024)

ISSN: 1029-8479, SCIE

Measurement of branching-fraction ratios and CP asymmetries in B± → DCP±K± decays at Belle and Belle II

Belle II Collaboration (I. Adachi, ..., N. Anh Ky, ...)

We report results from a study of B± → DK± decays followed by D decaying to CP eigenstates, where D indicates a D0 or D0 meson. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity-triangle angle ϕ3. The results are based on a combined analysis of the final data set of 772 × 106 BB¯ pairs collected by the Belle experiment and a data set of 198 × 106 BB¯ pairs collected by the Belle II experiment, both in electron-positron collisions at the Υ(4S) resonance. We measure the CP asymmetries to be ACP + = (+12.5 ± 5.8 ± 1.4)% and ACP − = (−16.7 ± 5.7 ± 0.6)%, and the ratios of branching fractions to be RCP + = 1.164±0.081±0.036 and RCP − = 1.151±0.074±0.019. The first contribution to the uncertainties is statistical, and the second is systematic. The asymmetries ACP + and ACP − have similar magnitudes and opposite signs; their difference corresponds to 3.5 standard deviations. From these values we calculate 68.3% confidence intervals of (8.5 ◦ < ϕ3 < 16.5 ◦ ) or (84.5 ◦ < ϕ3 < 95.5 ◦ ) or (163.3 ◦ < ϕ3 < 171.5 ◦ ) and 0.321 < rB < 0.465.

DOI: https://doi.org/10.48550/arXiv.2308.05048

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