Shu-Ping Lin ; Pao-Ti Chang

2023
National Taiwan University Taipei

Abstract: We report updated measurements of the branching ratio and the direct CP-violating asym- metry in B0 → KS0π0 decay at Belle II. The flavour information of the decay is obtained from the pair-produced neutral B partner Btag, and the direct CP asymmetry parame- ter is determined with the time-integrated method. We analyse the 2019-2022 Belle II data from e+e− collisions produced by the asymmetric-energy SuperKEKB collider at the Υ(4S) resonance. The data analysed contain 387 million BB pairs and correspond to an integrated luminosity of 362 fb−1. We obtain the branching fraction and the direct CP asymmetry B(B0 → K0π0) = (10.16 ± 0.65 ± 0.65) × 10−6, A(B0 → K0π0) = −0.06 ± 0.15 ± 0.05, where the first uncertainties are statistical and the second systematic. With other Belle II B → Kπ measurements of branching fractions and direct CP asymmetries, we compute the Kπ isospin sum rule to be IKπ = −0.03 ± 0.13 ± 0.05, which is in agreement with the standard model prediction of zero.

Note: Presented on 27 03 2023
Note: MSc