Measurement of time-dependent CP asymmetries in decays at Belle and Belle II

Abstract

We present a measurement of the time-dependent CP asymmetry in decays using a data set of 365 fb−1 recorded by the Belle II experiment and the final data set of 711 fb−1 recorded by the Belle experiment at the Υ(4S) resonance. The direct and mixing-induced time-dependent CP violation parameters C and S are determined along with two additional quantities, S+ and S−, defined in the two halves of the plane. The measured values are C = −0.17 ± 0.09 ± 0.04, S = −0.29 ± 0.11 ± 0.05, S+ = −0.57 ± 0.23 ± 0.10 and S− = 0.31 ± 0.24 ± 0.05, where the first uncertainty is statistical and the second systematic.