The electromagnetic form factors of $\Sigma$ and $\Sigma^0 \to \Lambda$ transition in the timelike region

TL;DR

This paper models the electromagnetic form factors of Sigma and Lambda-Sigma transitions in the timelike region using an extended vector meson dominance approach, incorporating excited meson states to match experimental data.

Contribution

It introduces an extended vector meson dominance model including excited mesons to accurately describe timelike electromagnetic form factors of hyperons.

Findings

The model reproduces experimental data on Sigma form factors.

The phi(3D) resonance explains near-threshold cross section enhancement.

The rho(3D) resonance is crucial for fitting Lambda-Sigma transition data.

Abstract

We investigate the $e^+e^-\to \Sigma\bar{\Sigma}$ and $e^+e^-\to \Lambda\bar{\Sigma}^0$ reactions within the extended vector meson dominance model. In addition to the ground state mesons $\rho$ and $\omega$, we consider the contributions of the excited states $\rho(3D)$, $\omega(3D)$, $\phi(3D)$, and $\rho(6D)$. It is found that the current experimental data on the $\Sigma$ electromagnetic form factors in timelike region can be well reproduced. And the $\phi(3D)$ resonance is essential to the near threshold enhancement of the cross section for the $e^+e^-\to \Sigma\bar{\Sigma}$ reaction. Furthermore, in the $e^+e^-\to \Lambda\bar{\Sigma}^0$ reaction, the $\rho(3D)$ is important to get a good fit for the experimental results.