Observation of double c(c)over-bar production in e+e- annihilation at √s≈10.6 GeV -: art. no. 142001

We report the observation of prompt J/psi via double c (c) over bar production from the e(+)e(-) continuum. In this process one c (c) over bar pair fragments into a J/psi meson while the remaining pair either produces a charmonium state or fragments into open charm. Both cases have been experimentally observed. We find cross sections of sigma[e(+)e(-)-->J/psieta(c)(gamma)]xB(eta(c)-->greater than or equal to4 charged)=(0.033(-0.006)(+0.007)+/-0.009) pb and sigma(e(+)e(-)-->J/psiD(*+)X)=(0.53(-0.15)(+0.19)+/-0.14) pb and infer sigma(e(+)e(-)-->J/psic (c) over bar)/sigma(e(+)e(-)-->J/psiX)=0.59(-0.13)(+0.15)+/-0.12. These results are obtained from a 46.2 fb(-1) data sample collected near the Y(4S) resonance, with the Belle detector at the KEKB collider.