A study of the two body decays $B^\pm\rightarrow X_{ c\bar c}K^\pm$, where X$_{ c\bar c}$ refers to one charmonium state, is reported by BaBar collaboration using a data sample of 424 fb$^{ -1}$. The absolute determination of branching fractions for these decays are significantly improved compared to previous BaBaR measurements. Evidence is found for the decay $B^+\rightarrow X(3872)K^+$ at the $3\sigma$ level. The absolute branching fraction ${ \cal B}(B^+\rightarrow X(3872)K^+) = (2.1\pm0.6({ \rm stat})\pm0.3({ \rm syst}))\times 10^{ -4}$ is measured for the first time. It follows that ${ \cal B}(X(3872)\rightarrow J/\psi\pi^+\pi^-)=(4.1\pm1.3)\%$, supporting the hypothesis of a molecular component for this resonance.
Categories: hep-ex
