Study of X(3872) in $B$ meson decays

Abstract

We present results on the X(3872), produced in $B^{+}\to X(3872)K^{+}$ and $B^0\to X(3872)K_S^0$ decays where $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$. We report the first statistically significant observation of $B^0\to X(3872)K_S^0$ and measure the ratio of branching fractions to be $\frac{\mathcal{B}(B^0\to X(3872)K^0)}{\mathcal{B}(B^{+}\to X(3872)K^{+})}=0.82\pm 0.22\pm 0.05$, consistent with unity. The mass difference between the X(3872) states produced in $B^{+}$ and $B^0$ decay is found to be $\delta M\equiv M_{X{K}^{+}}-M_{X{K}^0}=(+0.18\pm 0.89\pm 0.26)$ MeV/$c^2$, consistent with zero. In addition, we search for the X(3872) in the decay $B^0\to X(3872)K^{+}{\pi }^{-}$, $X(3872)\to J/\psi {\pi }^{+}{\pi }^{-}$. We measure $\mathcal{B}(B^0\to X(3872)(K^{+}{\pi }^{-}{)}_{NR})\times \mathcal{B}(X(3872)\to J/\psi {\pi }^{+}{\pi }^{-})=(8.1\pm 2.0_{-1.4}^{+1.1})\times 10^{-6}$ and we set the 90% C.L. limit, $\mathcal{B}(B^0\to X(3872)K^{\ast }(892{)}^0)\times \mathcal{B}(X(3872)\to J/\psi {\pi }^{+}{\pi }^{-})<3.4\times 10^{-6}$. The analysis is based on a 605 fb${}^{-1}$ data sample collected at the ${\rm Y}(4S)$ with the Belle detector at the KEKB collider.

arXiv comment10 pages, 5 figures, Contributed to the 34th International Conference On High Energy Physics (ICHEP 2008)