PANDA Website

The proton electromagnetic form factors (FF) in the space-like region (q2 < 0) have been measured for multiple decades using electron{proton scattering and Rosenbluth separation method. Recently developed polarization transfer technique resulted in a dierent value of extracted FF. It was suggested that the previously unaccounted hard two-photon exchange (TPE) eect, can be responsible for the discrepancy. The OLYMPUS experiment performed a high precision measurement of the TPE contribution via measurement of the positron to electron elastic scattering cross section ratio. It was performed at DESY using 2 GeV electron and positron beams and the BLAST spectrometer. A crucial part of the experiment was precise measurement of the integrated luminosity. The symmetric Moeller/Bhabha luminosity monitors, which were designed and built in Mainz, used Mller and Bhabha processes for luminosity measurements. The analysis of the collected SYMB data is presented in this work. In the time-like region, where q2 > 0, form factor data is scarce and only the ratio of electric to magnetic form factor have been measured so far. The PANDA experiment will be able to measure individual electric and magnetic time-like FF. Extensive feasibility studies of the proton form factor measurement have been performed using PandaRoot simulation framework. This include the signal pbar p -> e+e- selection, the main background pbar p -> pi+ pi- suppression, and investigation of possible sources of systematic uncertainties in the q2 range between 5.4 GeV^2 and 13.9 GeV^2. The estimated statistical and systematic accuracy of the proton FF extraction at PANDA is 2%-57%.