The electromagnetic form factors of $\Sigma$ and ${\Sigma }^0\to \Lambda$ 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 $\rho (3D)$, $\omega (3D)$, $\varphi (3D)$, 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 $\varphi (3D)$ 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.

Comments: 17 pages, 10 figures