Observation of the rare decay B0→K0SK±π∓

Abstract

We report an analysis of charmless hadronic decays of neutral B mesons to the final state K 0 S K ± π ∓ , using a data sample of ( 465 ± 5 ) × 10 6 B ¯¯¯ B events collected with the BABAR detector at the Υ ( 4 S ) resonance. We observe an excess of signal events with a significance of 5.2 standard deviations including systematic uncertainties and measure the branching fraction to be B ( B 0 → K 0 S K ± π ∓ ) = ( 3.2 ± 0.5 ± 0.3 ) × 10 − 6 , where the uncertainties are statistical and systematic, respectively.