Evidence for B+→¯¯¯¯K0K+ and B0→K0¯¯¯¯K0, and Measurement of the Branching Fraction and Search for Direct CP Violation in B+→K0π+

Abstract

We present evidence for the b → d penguin-dominated decays B + → ¯¯¯¯ K 0 K + and B 0 → K 0 ¯¯¯¯ K 0 in 227 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays collected with the BABAR detector. We measure the branching fractions B ( B + → ¯¯¯¯ K 0 K + ) = ( 1.5 ± 0.5 ± 0.1 ) × 10 − 6 ( < 2.4 × 10 − 6 ) and B ( B 0 → K 0 ¯¯¯¯ K 0 ) = ( 1.19 + 0.40 − 0.35 ± 0.13 ) × 10 − 6 , where the uncertainties are statistical and systematic, respectively. We also present improved measurements of the charge-averaged branching fraction B ( B + → K 0 π + ) = ( 26.0 ± 1.3 ± 1.0 ) × 10 − 6 and C P -violating charge asymmetry A C P ( K 0 π + ) = − 0.09 ± 0.05 ± 0.01 , where the uncertainties are statistical and systematic, respectively.