Electron Quasielastic Scattering at High Energy from $^{56}$Fe, What Suppression?

Abstract

Quasielastic electron scattering $(e,e')$ from $^{56}$Fe is calculated at large electron energies (2-4 GeV) and large three momentum transfer (0.5-1.5 GeV/c). We use a relativistic mean-field single particle model for the bound and continuum nucleon wavefunctions based on the $\sigma-\omega$ model and we include the effects of electron Coulomb distortion in the calculation. The calculations are compared to high energy data from SLAC and more recent data from Jefferson Laboratory, particularly for kinematics where the energy transfer is less than 500 to 600 MeV and the quasielastic process is expected to dominate the cross section. The effects of the predicted weakening of the strong scalar and vector potentials of the $\sigma-\omega$ model at high energy are investigated. Possible evidence for `longitudinal suppression' or modifications of nucleon form factors in the medium is considered, but neither is necessary to explain the quasielastic data for four momentum transfers less than 1 (GeV/c)$^2$.