Observation of e(+)e(-)-> K(+)K(-)J/psi via initial-state radiation at Belle

Abstract

The process e(+)e(-)-> K(+)K(-)J/psi is observed for the first time via initial-state radiation. The cross section of e(+)e(-)-> K(+)K(-)J/psi for center-of-mass energies between threshold and 6.0 GeV is measured using 673 fb(-1) of data collected with the Belle detector on and off the Upsilon(4S) resonance. No significant signal for Y(4260)-> K(+)K(-)J/psi is observed, and we determine B(Y(4260)-> K(+)K(-)J/psi)Gamma(Y(4260)-> e(+)e(-))< 1.2 eV/c(2) at a 90% confidence level. We also find evidence for e(+)e(-)-> K(S)(0)K(S)(0)J/psi in the same data sample.