The Electromagnetic Form Factors of Σ and Σ⁰→Λ Transition in the Timelike Region

We investigate the e^+e^-\to \varSigma\bar\varSigma and e^+e^-\to \varLambda\bar\varSigma^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(2850). It is found that the current experimental data on the \varSigma electromagnetic form factors in timelike region can be well reproduced. The \phi(3D) resonance is essential to the near threshold enhancement of the cross-section for the e^+e^-\to \varSigma\bar\varSigma reaction. Furthermore, in the e^+e^-\to \varLambda\bar\varSigma^0 reaction, the \rho(3D) is important to get a good fit for the experimental results.