Feasibility studies of the time-like proton electromagnetic form factor measurements with PANDA at FAIR

The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the annihilation of \(\bar p +p \) into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction \(\bar p +p \to e^++ e^-\) can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of \(q^2\simeq 14\) (GeV/c)\(^2\). The total \(\bar p +p\to e^++e^-\) cross section will be measured up to \(q^2\simeq 28\) (GeV/c)\(^2\). The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.