Possible contributions to $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ due to intermediate meson rescatterings

Abstract

Inspired by the obvious discrepancies between experiment and non-relativistic QCD (NRQCD) studies of $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at $\sqrt{s}\simeq 10.6$ GeV, we investigate contributions from intermediate meson loops as long-range interaction transitions to this process. The intermediate meson loops include $D\bar{D}({\bar{D}}^{\ast })$, $D{\bar{D}}^{\ast }(Dor{D}^{\ast })$, $D^{\ast }{\bar{D}}^{\ast }(D)$ and corresponding $D_s$ intermediate mesons. With the constraints from experimental data on the vertex couplings, we find that the intermediate meson loops account for $2.7\sim 6.7fb$ of the cross sections within a reasonable range of cut-off energies of the factor parameter. We also investigate contributions from the absorptive part and find that it accounts for approximately $0.58\sim 1.38fb$. These results imply that contributions from long-range interaction transitions may still play a role in such an energy region.

Comments: revised version to appear in Phys. Rev. D