Nuclear Medium Effects in the Relativistic Treatment of Quasifree Electron Scattering

Non-relativistic reduction of the S-matrix for the quasifree electron scattering process $A\left(~e, e'p~\right)A-1$ is studied in order to understand the source of differences between non-relativistic and relativistic models. We perform an effective Pauli reduction on the relativistic expression for the S-matrix in the one-photon exchange approximation. The reduction is applied to the nucleon current only; the electrons are treated fully relativistically. An expansion of the amplitude results in a power series in the nuclear potentials. The series is found to converge rapidly only if the nuclear potentials are included in the nuclear current operator. The results can be cast in a form which reproduces the non-relativistic amplitudes in the limit that the potentials are removed from the nuclear current operator. Large differences can be found between calculations which do and do not include the nuclear potentials in the different orders of the nuclear current operator. In the high missing momentum region we find that the non-relativistic calculations with potentials included in the nuclear current up to second order give results which are close to those of the fully relativistic calculation. This behavior is an indication of the importance of the medium modifications of the nuclear currents in this model, which are naturally built into the relativistic treatment of the reaction.Comment: Latex, 26 pages including 5 uuencoded postscript figures. accepted for publication in Phys. Rev. C

Coulomb effects in quasielastic electron scattering

Coulomb distortion plays an important role in interpreting both (e,e{prime}) and (e,e,{prime}p) reactions in the quasielastic region. A fully distorted partial wave calculation is presented, and the results are compared with the widely-used plane wave approximation and other distorted-wave calculations. The new calculation seems to give higher occupation numbers in the (e,e{prime}p) reactions. The usefulness of the (e,e{prime}p) reaction in studying different nuclear optical potentials is discussed. Also considered are the effects of electron Coulomb distortion in the separation of longitudinal and transverse structure functions in (e.e{prime})