Angular distributions for knockout and scattering of protons in the eikonal approximation.

The advent of new electron accelerators with few-GeV beam energies makes the (e,ep) reaction a promising tool for investigating new aspects of the electromagnetic interaction. To this purpose it is crucial to set the scale of Final-State Interactions (FSI) at high ejectile energies. Usually, the problem is faced by mutuating wellestablished results of the Glauber method in the framework of elastic (p,p) scattering. Since the generalization of this eikonal approximation to the (e,ep) case is not straightforward, we have analyzed the constraints which make the comparison a meaningful one, using the C(e,ep)Bs1/2 and Bs1/2(p,p) reactions with outgoing-proton momenta of 4 GeV/c as a test case. The FSI dominance at large deflection angles produces in the distributions a universal behaviour resembling the coherent diffractive scattering between the ejected proton and the (residual) nucleus. Because of the selected sensitivity of the (e,ep) distribution to different theoretical ingredients depending on different values of the deflection angle (or transverse missing momentum), it is argued that the previous comparison with elastic proton scattering may represent a convenient tool to disentangle effects due to the (hard) electromagnetic vertex from (exotic) effects related to the propagation of the struck hadron through the nuclear medium.