We report a study of the decay D0→K0SK0S using 921 fb−1 of data collected at or near the Υ(4S) and Υ(5S) resonances with the Belle detector at the KEKB asymmetric energy e+e− collider. The measured time-integrated CP asymmetry is ACP(D0→K0SK0S)=(−0.02±1.53±0.02±0.17)%, and the branching fraction is B(D0→K0SK0S)=(1.321±0.023±0.036±0.044)×10−4, where the first uncertainty is statistical, the second is systematic, and the third is due to the normalization mode (D0→K0Sπ0). These results are significantly more precise than previous measurements available for this mode. The ACP measurement is consistent with the standard model expectation.
Physical Review Letters
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