none576siWe measure the absolute branching fraction for D0→K-π+ using partial reconstruction of B̄0→D*+X -ν̄ decays, in which only the charged lepton and the pion from the decay D*+→D0π+ are used. Based on a data sample of 230×106 BB̄ pairs collected at the Υ(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we obtain B(D0→K-π+)=(4.007±0.037±0.072) %, where the first uncertainty is statistical and the second is systematic. © 2008 The American Physical Society.noneAubert, B; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prudent, X.; Tisserand, V.; Zghiche, A.; Garra Tico, J.; Grauges, E.; Lopez, L.; Palano, A.; Eigen, G.; Ofte, I.; Stugu, B.; Sun, L.; Abrams, G.S.; Battaglia, M.; Brow...