Study of the electromagnetic form factors of the nucleons in the timelike region

The electromagnetic form factors G ₄ and G ₌ of the proton and neutron in the timelike region are extracted in a study of the processes e^+ e^- pp and e^+ e^- nn. The reaction amplitude is evaluated within the distorted wave Born approximation, with the interaction of the antinucleon-nucleon (NN) pair taken into account. The latter is constructed within SU (3) chiral effective field theory up to the next-to-leading order. An excellent description of the e^+ e^- NN data in the energy region from the NN threshold up to center-of-mass energies E ₂₌=2. 2~GeV is achieved. Results for the electromagnetic form factors G ₄, G ₌, G ₄/G ₌, and the subtracted effective form factors, G ₎ₒ₂, are provided. These can be helpful for further studies of the properties of the nucleons.