Seminar on Theoretical Nuclear Physics
17.05.11 16:15
Two-photon exchange in the space-like and time-like region
Julia Guttmann (Mainz)
In the extraction of electromagnetic form factors from electron-proton scattering the discrepancy between data of unpolarized Rosenbluth measurements and of polarization experiments has triggered a whole new field studying the influence of two-photon exchange corrections. Using the available cross section and polarization data for elastic electron-proton scattering, we provide an extraction of the two-photon exchange amplitudes and present predictions for forthcoming experiments. We also discuss the influence of two-photon exchange in the time-like region. An estimate of the two-photon contribution at large momentum transfer, which involves the proton distribution amplitudes, will be discussed at leading order in perturbative QCD.
(Seminarraum II)