$N\bar{N}$ production in $e^{+}{e}^{-}$ annihilation near the threshold revisited

Abstract

Production of $p\bar{p}$ and $n\bar{n}$ pairs in $e^{+}{e}^{-}$ annihilation near the threshold of the process is discussed with account for the new experimental data appeared recently. Since a significant part of these new data was obtained at energies noticeably exceeding the threshold, we also take into account the form factor describing the amplitude of $N\bar{N}$ pair production at small distances. The effective optical potential, which describes a sharp dependence of the $N\bar{N}$ production cross sections near the threshold, consists of the central potential for $S$ and $D$ waves and the tensor potential. These potentials differ for the states with isospin $I=0$ and $I=1$ of $N\bar{N}$ pair. The optical potential describes well $N\bar{N}$ scattering phases, the cross sections of $p\bar{p}$ and $n\bar{n}$ production in $e^{+}{e}^{-}$ annihilation near the threshold, the electromagnetic form factors $G_E$ and $G_M$ for protons and neutrons, as well as the cross sections of the processes $e^{+}{e}^{-}\to 6\pi$ and $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}$.

Comments: 8 pages, 5 figures