# ICHEP 2020

July 28, 2020 to August 6, 2020
virtual conference
Europe/Prague timezone

## Measurement of absolute branching fractions of $B \to K + X_{cc}$

Jul 29, 2020, 5:20 PM
15m
virtual conference

#### virtual conference

Talk 06. Strong Interactions and Hadron Physics

### Speaker

Fergus Wilson (Science and Technology Facilities Council STFC (GB))

### 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.

### Primary author

Fergus Wilson (Science and Technology Facilities Council STFC (GB))