Deep inelastic lepton scattering in nuclei at x > 1 and the nucleon spectral function

The nuclear structure function F_{2 A}( x) has been studied in the Bjorken limit for ( l, l') scattering on nuclei in the region of x > 1 and was found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly the correlations between momenta and energies in the region of large momenta. Calculations were done in a local density approximation using two different spectral functions for nuclear matter. Results are compared to those obtained for a spectral function which has been evaluated directly for the finite nucleus, ¹⁶O, under consideration. For values of x around 1.5 and larger the quasiparticle contribution is negligible, thus stressing the sensitivity of the present reaction to the dynamical properties of nuclei beyond the shell model approach. Several approximations which are usually employed in studies of the EMC effect have been analyzed and their inaccuracy in this region is demonstrated. The results stress the fact that the nuclear structure function contains important information on nuclear dynamical correlations. Therefore further measurements of F_{2 A}( x) in that region and for many nuclei would be most welcome.