We present an update of the study of the Y(4260) resonance, produced in the process $e^+e^-\to\gamma_{ ISR} \pi^+\pi^-J/\psi$ using initial-state radiation events at the PEP-II $e^+e^-$ storage rings. This study is based on 454fb$^{ -1}$ of data recorded with the { \slshape B\kern-0.1em{ \smaller A}\kern-0.1em B\kern-0.1em{ \smaller A\kern-0.2em R}} detector at a center-of-mass energy in the $\Upsilon(4S)$ resonance region. From a fit with a single non-relativistic Breit-Wigner shape we obtain updated parameters for the Y(4260) resonance which are $m_Y = 4252 \pm6 ^{ +2}_{ -3}$MeV/c$^2$ and $\Gamma_Y = 105 \pm 18^{ +4}_{ -6}$MeV/c$^2$; we also measure ${ \calB}(\pi^+\pi^-J/\psi)\Gamma_{ e^+e^-} = (7.5\pm 0.9 \pm0.8)$ eV. We cannot confirm the recent BELLE observation of a broad structure around 4.05GeV/c$^2$ in this decay mode.
Categories: hep-ex