Evidence of psi(3770) non-DD-bar Decay to J/psi pi+pi-

Abstract

Evidence of $\psi(3770)$ decays to a non-${D \bar D}$ final state is observed. A total of $11.8 \pm 4.8 \pm 1.3$ $\psi(3770) \to \PPJP$ events are obtained from a data sample of 27.7 $\rm {pb^{-1}}$ taken at center-of-mass energies around 3.773 GeV using the BES-II detector at the BEPC. The branching fraction is determined to be $BF(\psi(3770) \to \PPJP)=(0.34\pm 0.14 \pm 0.09)%$, corresponding to the partial width of $\Gamma(\psi(3770) \to \PPJP) = (80 \pm 33 \pm 23)$ keV.