none544siWe present measurements of the branching fraction and time-dependent CP asymmetries in B0→J/ψπ0 decays based on 466×106 Υ(4S)→BB̄ 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. © 2008 The American Physical Society.noneAubert, B; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Tico, J. Garra; Grauges, E.; Lopez, L.; Palano, A.; Pappagallo, M.; Eig...