QUASI-FREE PION ELECTROPRODUCTION FROM NUCLEI IN THE DELTA-REGION

We, present calculations of the reaction A(e,e' pi N)B in the distorte d (and plane) wave impulse approximation. The reaction allows for the study of the production process in the nuclear medium without being ob scured by the details of nuclear transition densities. First, a pion e lectroproduction operator suitable for nuclear calculations is obtaine d by extending the Blomqvist-Laget photoproduction operator to the vir tual photon case, which describes the existing data reasonably well. I t is applied in nuclei to predict nuclear cross sections under a varie ty of kinematic arrangements. Issues such as the effects of the interf erence of the Delta resonance with the background, sensitivities to th e quadrupole component of the Delta excitation and to the electromagne tic form factors, and the role of final-state interactions are studied in detail. It is found that the longitudinal and the LT interference structure functions in (e,e' pi(0)N) are sufficiently sensitive to ext ract medium modifications of the Delta quadrupole component. Methods o n how to experimentally separate the various pieces in the coincidence cross section are suggested. Finally, the model is compared to a rece nt SLAC experiment.