Measurement of the Absolute Branching Fraction of D^{0}→K^{-}π^{+}

We measure the absolute branching fraction for D-0 --> K-pi(+) using partial reconstruction of (B) over bar (0) --> D(*+)Xl(-)(nu) over bar (l) decays, in which only the charged lepton and the pion from the decay D*+ --> D-0 pi(+) are used. Based on a data sample of 230x10(6) (B) over bar pairs collected at the Y(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC, we obtain B(D-0 --> K-pi(+))=(4.007 +/- 0.037 +/- 0.072)%, where the first uncertainty is statistical and the second is systematic.