Relativistic approaches to structure functions of nuclei

We employ a propagator technique to derive a new relativistic 1/|q| expansion of the structure function of a nucleus, composed of point nucleons. We exploit nonrelativistic features of low-momentum nucleons in the target and only treat relativistically the nucleon after absorption of a high-momentum virtual photon. The new series permits a three-dimensional reduction of each term and a formal summation of all final state interaction terms. We then show that a relativistic structure function can be obtained from its nonrelativistic analog by a mere change of a scaling variable and the addition of an energy shift. We compare the obtained result with an ad hoc generalized Gersch-Rodriguez-Smith theory, previously used in computations of nuclear structure functions.