Possible contributions to $e^+e^- \to J/\psi + \eta_c$ due to intermediate meson rescatterings

TL;DR

This paper explores how intermediate meson rescatterings could explain the discrepancy between experimental results and NRQCD predictions for the $e^+e^- o J/ + \u03b5_c$ process at around 10.6 GeV, highlighting the significance of long-range interactions.

Contribution

It introduces the calculation of intermediate meson loop contributions to the process, showing they can significantly impact the cross section and potentially resolve existing discrepancies.

Findings

Intermediate meson loops contribute 2.7 to 6.7 fb to the cross section.

Absorptive parts contribute approximately 0.58 to 1.38 fb.

Long-range interactions may influence the process at this energy region.

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 $D\bar D(\bar D^\ast)$, $D\bar D^\ast(D {or} D^\ast)$, $D^\ast \bar D^\ast(D)$ 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 $2.7\sim 6.7 fb$ 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 $0.58\sim 1.38 fb$. These results imply that contributions from long-range interaction transitions may still play a role in such an energy region.