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

Abstract

Abstract The electromagnetic form factors G E and G M of the proton and neutron in the timelike region are extracted in a study of the processes e + e − → p ¯ p $$ \overline{p}p $$ and e + e − → n ¯ n $$ \overline{n}n $$ . The reaction amplitude is evaluated within the distorted wave Born approximation, with the interaction of the antinucleon-nucleon N ¯ N $$ \left(\overline{N}N\right) $$ pair taken into account. The latter is constructed within SU(3) chiral effective field theory up to next-to-leading order. An excellent description of the e + e − → N ¯ N $$ \overline{N}N $$ data in the energy region from the N ¯ N $$ \overline{N}N $$ threshold up to center-of-mass energies E cm = 2.2 GeV is achieved. Results for the electromagnetic form factors G E, G M, G E/G M, and the subtracted effective form factors, G osc, are provided. These can be helpful for further studies of the properties of the nucleons.

Keywords

• Chiral Lagrangian
• Properties of Hadrons