Observation of X (3872) in B →x (3872)Kπ decays

Abstract

We report the first observation of B0→X(3872)(K+π-) and evidence for B+→X(3872)(K0π+). We measure the product of branching fractions for the former to be B(B0→X(3872)(K+π-))×B(X(3872)→J/ψπ+π-)=(7.9±1.3(stat)±0.4(syst))×10-6 and find that B0→X(3872)K∗(892)0 does not dominate the B0→X(3872)K+π- decay mode. We also measure B(B+→X(3872)(K0π+))×B(X(3872)→J/ψπ+π-)=(10.6±3.0(stat)±0.9(syst))×10-6. This study is based on the full data sample of 711fb-1 (772×106BB¯ pairs) collected at the Υ(4S) resonance with the Belle detector at the KEKB collider.