Direct<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math>Violating Asymmetry in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>B</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>π</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>Decays

We present a measurement of the direct CP violating asymmetry in the decay B0-->K+pi(-) using a data sample of 227x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC. We observe a total signal yield of nK-(pi(+))+nK+(pi(-))=1606+/-51 decays and measure the asymmetry (nK-(pi(+))-nK+(pi(-)))/(nK-(pi(+))+nK+(pi(-)))=-0.133+/-0.030(stat)+/-0.009(syst). The probability of observing such an asymmetry in the absence of direct CP violation is 1.3x10(-5), corresponding to 4.2 standard deviations.