Problems of double-charm production in e+e- annihilation at √s=10.6 GeV

Using the nonrelativistic QCD (NRQCD) factorization formalism, we calculate the color-singlet cross sections for exclusive production processes e(+) + e(-) --> J/psi + n(c) and e(+) + e(-) --> J/psi + chi(cJ) (J = 0, 1, 2) at the center-of-mass energy roots = 10.6 GeV. The cross sections are estimated to be 5.5 fb, 6.7 fb, 1.1 fb, and 1.6 fb for eta(C), chi(c0), chi(c1), and chi(c2), respectively. The calculated J/psi + eta(c) production rate is smaller than the recent Belle data by about an order of magnitude, which might indicate the failure of perturbative QCD calculation to explain the double-charmonium production data. The complete O(alpha(s)(2)) color-singlet cross section for e(+) + e(-) --> chi(c0) + c (c) over bar is calculated. In addition, we also evaluate the ratio of exclusive to inclusive production cross sections. The ratio of J/psieta(c) production to J/psic (c) over bar production could be consistent with the experimental data. (C) 2003 Published by Elsevier Science B.V.