Observation of Decays B0→D(*)+sπ− and B0→D(*)−sK+

Abstract

We report the observation of decays B 0 → D ( * ) + s π − and B 0 → D ( * ) − s K + in a sample of 230 × 10 6 Υ ( 4 S ) → B ¯¯¯ B events recorded with the BABAR detector at the SLAC PEP-II asymmetric-energy e + e − storage ring. We measure the branching fractions B ( B 0 → D + s π − ) = ( 1.3 ± 0.3 ( stat ) ± 0.2 ( syst ) ) × 10 − 5 , B ( B 0 → D − s K + ) = ( 2.5 ± 0.4 ( stat ) ± 0.4 ( syst ) ) × 10 − 5 , B ( B 0 → D * + s π − ) = ( 2.8 ± 0.6 ( stat ) ± 0.5 ( syst ) ) × 10 − 5 , and B ( B 0 → D * − s K + ) = ( 2.0 ± 0.5 ( stat ) ± 0.4 ( syst ) ) × 10 − 5 . The significances of the measurements to differ from zero are 5, 9, 6, and 5 standard deviations, respectively. This is the first observation of B 0 → D + s π − , B 0 → D * + s π − , and B 0 → D * − s K + decays.