Is the BELLE result for the cross section e+e- -> J/psi+eta_c a real difficulty for QCD ?

Abstract

It is shown that difficulties in reconciling the values of the cross section e+e- -> J/psi+eta_c measured at BELLE and calculated within non-relativistic QCD (NRQCD) are caused not by some misinterpretation of the data or other exotic explanations, but by poor applicability of NRQCD to such processes. We use general theory of hard exclusive processes in QCD together with more realistic models of charmonium wave functions, and show that the BELLE result can be naturally explained.

Figures (2)

• Figure 1: One of the four similar diagrams for the form factor $F_{J/\psi\,\eta_c}$.
• Figure 2: The shape of the wave function $\phi_o(x,v^2)$ for: $v^2=1$ -- light quarks (asymptotic); $v^2=0.30$ -- charmonium; $v^2=0.08$ -- bottomonium.