Evidence for CP Violation in B0→J/ψπ0 Decays

We present measurements of the branching fraction and time-dependent CP asymmetries in B0→J/ψπ0 decays based on 466×106 Υ(4S)→BB̅ events collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. We measure the CP asymmetry parameters S=-1.23±0.21(stat)±0.04(syst) and C=-0.20±0.19(stat)±0.03(syst), where the measured value of (S, C) is 4.0 standard deviations from (0, 0) including systematic uncertainties. The branching fraction is determined to be B(B0→J/ψπ0)=[1.69±0.14(stat)±0.07(syst)]×10-5.