Photoinduced Two-Nucleon Knockout: A Kinematical Study in Nuclear Matter

The contributions of short-range nucleon-nucleon correlations, meson exchange current (MEC) corrections and the influence of Delta isobar excitations (isobaric currents, IC) on photon induced two-nucleon knockout reactions are investigated. The nuclear structure functions are evaluated for the system of infinite nuclear matter. This allows a systematic investigation of the relative importance of the various contributions (MEC, IC and correlations) in different kinematical regions. Nucleon-nucleon (NN) correlations derived from a realistic NN interaction by solving the Bethe-Goldstone equation yield significant changes in the structure functions W_L and W_T of the (e,e'pn) and (e,e'pp) reactions. This is true in particular for the so-called 'super parallel' kinematics at momentum transfers which can be measured e.g. at MAMI in Mainz.