Measurement of the branching fraction and time-dependent CP asymmetry for B0 →j /ψπ0 decays

Abstract

We measure the branching fraction and time-dependent CP-violating asymmetry for B0→J/ψπ0 decays using a data sample of 711 fb-1 collected on the (4S) resonance by the Belle experiment running at the KEKB e+e- collider. The branching fraction is measured to be B(B0→J/ψπ0)=[1.62±0.11(stat)±0.06(syst)]×10-5, which is the most precise measurement to date. The measured CP asymmetry parameters are S=-0.59±0.19(stat)±0.03(syst) and A=-0.15±0.14(stat)+0.04-0.03(syst). The mixing-induced CP asymmetry (S) differs from the case of no CP violation by 3.0 standard deviations, and the direct CP asymmetry (A) is consistent with zero.