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

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.