Perturbative QCD analysis of exclusive J/\psi+\eta_c production in e^+e^- annihilation

TL;DR

This paper presents a perturbative QCD analysis of exclusive J/psi plus eta_c production in electron-positron annihilation, incorporating higher twist effects and a light-front quark model to improve cross section predictions.

Contribution

It introduces a nonfactorized perturbative QCD approach with the light-front quark model, going beyond the peaking approximation and including all higher twist terms at leading order.

Findings

Nonfactorized analysis increases cross section estimates by a factor of 3-4.

Calculated quark distribution amplitudes and decay constants for J/psi and eta_c.

Comparison shows the nonfactorized approach enhances traditional NRQCD results.

Abstract

We analyze the exclusive charmonium $J/\psi+\eta_c$ pair production in $e^+e^-$ annihilation using the nonfactorized perturbative QCD and the light-front quark model(LFQM) that goes beyond the peaking approximation. We effectively include all orders of higher twist terms in the leading order of QCD coupling constant and compare our nonfactorized analysis with the usual factorized analysis in the calculation of the cross section. We also calculate the quark distribution amplitudes, the Gegenbauer moments, and the decay constants for $J/\psi$ and $\eta_c$ mesons using our LFQM. Our nonfactorized result enhances the NRQCD result by a factor of $3\sim4$ at $\sqrt{s}=10.6$ GeV.