On the electromagnetic form factors of hadrons in the time-like region near threshold

Abstract

Hadron electromagnetic form factor in the time-like region at the boundary of the physical region is considered. The energy behavior of the form factor is shown to be determined by the strong hadron-antihadron interaction. Imaginary parts of the scattering lengths for $p\bar{p}$, $\Lambda\bar{\Lambda}$, $\Lambda\bar{\Sigma}^0 (\bar{\Lambda}{\Sigma}^0)$ and ${\Sigma}^0\bar{\Sigma}^0$ are estimated. Developed approach enables us to estimate imaginary part of the scattering volume from $D^*\bar{D^*}$ experimental data. The form factor energy behavior away from the threshold is obtained within a semiphenomenological model of hadron-antihadron interaction.