The electromagnetic form factors of the proton in the timelike region

Understand

The reactions ppbar -> e+e- and e+e- -> ppbar are analyzed in the near-threshold region.

• Specific emphasis is put on the role played by the interaction in the initial- or final antinucleon-nucleon state which is taken into account rigorously.
• For that purpose a recently published NNbar potential derived within chiral effective field theory and fitted to results of a new partial-wave analysis of ppbar scattering data is employed.
• Our results provide strong support for the conjecture that the pronounced energy dependence of the e+e- <-> ppbar cross section, seen in pertinent experiments, is primarily due to the ppbar interaction.