Nuclear transparency to intermediate-energy protons

Nuclear transparency in the (e,${\mathit{e}}^{\prime }$p) reaction for 135≤${\mathit{T}}_{\mathit{p}}$≤800 MeV is investigated using the distorted-wave approximation. Calculations using density-dependent effective interactions, both empirical and theoretical, are compared with phenomenological optical potentials. We find that nuclear transparency is well correlated with proton absorption and neutron total cross sections and that calculations using density-dependent effective interactions provide the best agreement with data. Nuclear transparency calculations are compared with recent electron scattering data for ${\mathit{Q}}^2$<2 (GeV/c${)}^2$. For ${\mathit{T}}_{\mathit{p}}$≲200 MeV we find that there is considerable sensitivity to the choice of optical model and that the empirical effective interaction provides the best agreement with the data, but remains 5–10 % low. For ${\mathit{T}}_{\mathit{p}}$≳300 MeV we find that there is much less difference between these models, but that the calculations significantly underpredict transparency data and that the discrepancy increases with A. The differences between Glauber and optical model calculations are related to their respective definitions of the semi-inclusive cross section. By using a more inclusive summation over final states the Glauber model emphasizes nucleon-nucleon inelasticity, whereas with a more restrictive summation the optical model emphasizes nucleon-nucleus inelasticity; experimental definitions of the semi-inclusive cross section lie between these extremes. © 1996 The American Physical Society.