Speaker
Description
We present measurements of absolute branching fractions of the two-body decays of $B$ mesons $B \to K + X_{cc}$, where $X_{cc}$ is a charmonium state, by using a data set corresponding to about 470 fb$^{-1}$ collected by the $BABAR$ detector at the PEP-II $e^+e^-$ collider. For events in which one $B$ is fully reconstructed, the charmonium spectrum can be observed in an unbiased way by looking at the distribution of the $K$ momentum in the rest frame of the recoiling $B$.
The absolute branching fraction $B^+ \to K^+ X(3872)$ is measured for the first time at 3-sigma level, and from it a branching fraction for $BF(X(3872)\to J/\psi \pi^+ \pi^-) = (4.1\pm 1.3)\%$ is derived, supporting the hypothesis of a molecular component for this resonance.
