Study of $B\to X(3872)K\pi$ at Belle

Abstract

We report the first observation of $B^0\to X(3872)(K^{+}{\pi }^{-})$ and evidence for $B^{+}\to X(3872)(K^0{\pi }^{+})$. The product of branching fractions for the former decay mode is measured to be ${\cal B}(B^0 \to X(3872) (K^+ π^-)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (7.9 \pm 1.3(\mbox{stat.})\pm 0.4(\mbox{syst.})) \times 10^{-6}$ and also find that $B^0\to X(3872)K^{\ast }(892{)}^0$ does not dominate the $B^0\to X(3872)K^{+}{\pi }^{-}$ decay mode in contrast to other charmonium states like ${\psi }^{\prime }$. The product of branching fractions for the latter decay mode is measured to be ${\cal B}(B^+ \to X(3872) (K^0 π^+)) \times {\cal B}(X(3872) \to J/ψπ^+ π^-) = (10.6 \pm 3.0(\mbox{stat.}) \pm 0.9(\mbox{syst.})) \times 10^{-6}$. This study is based on the full and final data sample of 711~fb${}^{-1}$ ($772\times 10^{6}B\bar{B}$ pairs) collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB collider.

arXiv comment8 Pages, 3 Figures, Charm 2015 Conference Presented by V. Bhardwaj for Belle Collaboration