The cross section of the process $e^+e^- \to \Lambda\bar{\Lambda}$ in the vicinity of charmonium $\psi(3770)$ including three-gluon and $D$-meson loop contributions

TL;DR

This paper calculates the cross section of $e^+e^- o \Lambdaar{\Lambda}$ near the $\psi(3770)$ resonance, considering $D$-meson loop and three-gluon contributions, successfully matching experimental data and deriving the $\\Lambda$ electromagnetic form factor.

Contribution

It introduces a combined analysis of $D$-meson loop and three-gluon contributions to the cross section near $\psi(3770)$, providing a better understanding of the process and form factors.

Findings

Both contributions significantly affect the cross section.

The combined model reproduces experimental data well.

A fit for the $\\Lambda$ electromagnetic form factor is obtained.

Abstract

The total cross section of the process $e^+e^- \to \Lambda\bar{\Lambda}$ is calculated within the energy range close to the mass of $\psi(3770)$ charmonium state. Two different contributions were considered: the $D$-meson loop and the three gluon charmonium annihilation one. Both of them contribute noticeably and in sum fairly reproduce the data. Large relative phase for these contributions are generated with respect to the pure electromagnetic mechanism. As a by product the fit for the electromagnetic form factor of $\Lambda$-hyperon is obtained for the large momentum transferred region.