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

TL;DR

This paper revisits proton-antiproton and neutron-antineutron production in electron-positron annihilation near threshold, incorporating new experimental data and form factors to refine the optical potential model for better understanding of cross sections and form factors.

Contribution

It introduces an improved optical potential model accounting for recent data and form factors, enhancing the description of Nar{N} production near threshold.

Findings

Optical potential accurately describes Nar{N} scattering phases.

Model fits well with experimental cross sections and form factors.

Provides insights into isospin dependence of Nar{N} interactions.

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 $e^{+}e^{-}\to6\pi$ and $e^{+}e^{-}\to K^{+}K^{-}\pi^{+}\pi^{-}$.