Abstract
We report the first observation of the decays . The data sample of used in this analysis corresponds to pairs, collected at the resonance by the Belle detector at the KEKB asymmetric-energy collider. We observe and excesses of events for the two decay modes and measure the branching fractions of and to be and , respectively, where the first uncertainties are statistical and the second are systematic. These results are not compatible with the predictions based on the generalized factorization approach. In addition, a threshold enhancement in the dibaryon () system is observed, consistent with that observed in similar decays.
- Received 11 September 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.221803
© 2015 American Physical Society