Abstract
We present a measurement of time-dependent rate asymmetries in B-0 -> phi K-s(0) decays to search for non-standard-model physics in b -> q (q) over bars transitions. The data sample is collected with the Belle II detector at the SuperKEKB asymmetric-energy e(+)e(-) collider in 2019-2022 and contains (387 +/- 6) x 10(6) bottomantibottom mesons from gamma(4S) 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 = -0.31 +/- 0.20 +/- 0.05 and S = 0.54 +/- 0.26(-0.08)(+0.06), respectively, where the first uncertainties are statistical and the second are systematic.
The results are compatible with the CP asymmetries observed in b -> c (c) over bars transitions.