PHYSICAL REVIEW D 108, , 072012 (2023)

ISSN: 2470-0029, SCIE

Measurement of CP asymmetries in B0 → ϕK0 s decays with Belle II

The Belle II collaboration (I. Adachi, ..., N. Anh Ky, ...)

We present a measurement of time-dependent rate asymmetries in B0 → ϕK0 S decays to search for non-standard-model physics in b → qqs¯ transitions. The data sample is collected with the Belle II detector at the SuperKEKB asymmetric-energy eþe− collider in 2019–2022 and contains ð387 6Þ × 106 bottomantibottom mesons from ϒð4SÞ resonance decays. We reconstruct 162 17 signal events and extract the charge-parity (CP) violating parameters from a fit to the distribution of the proper-decay-time difference of the two B mesons. The measured direct and mixing-induced CP asymmetries are C ¼ −0.31 0.20 0.05 and S ¼ 0.54 0.26þ0.06 −0.08 , respectively, where the first uncertainties are statistical and the second are systematic. The results are compatible with the CP asymmetries observed in b → ccs¯ transitions.

DOI: 10.1103/PhysRevD.108.072012