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. We propose a simple phenomenological model of the h h ¯ interaction that describes the form factor behaviour in the region where scattering length approximation fails and estimate on its basis imaginary part of the scattering lengths (volumes) for Λ Λ ¯ , Λ Σ ¯ 0 ( Λ ¯ Σ 0 ) , Σ 0 Σ ¯ 0 and D ∗ D ∗ ¯ from present experimental data. The developed approach enables us to analyze the existence of baryon–antibaryon ( B B ¯ ) near threshold resonances. The experiments to extract detailed information on the near threshold B B ¯ interaction from hadron form factor energy behavior are suggested.