Measurement of CP Asymmetries in B0→KS0π0γ Decays at Belle II

Abstract

We report measurements of time-dependent CP asymmetries in B0→KS0π0γ decays based on a data sample of (388±6)×106 BB ̄ events collected at the Υ(4S) resonance with the Belle II detector. The Belle II experiment operates at the SuperKEKB asymmetric-energy e+e- collider. We measure decay-time distributions to determine CP -violating parameters S and C. We determine these parameters for two ranges of KS0π0 invariant mass: m(KS0π0)(0.8,1.0) GeV/c2, which is dominated by B0→K∗0(→KS0π0)γ decays, and a complementary region m(KS0π0)(0.6,0.8)(1.0,1.8) GeV/c2. Our results have improved precision as compared to previous measurements and are consistent with theory predictions