Deep inelastic lepton-nucleus scattering from the light-cone quantum field theory

Abstract

The authors show that for deep inelastic lepton-nucleus scattering, the conditions which validate the impulse approximation are hardly satisfied when using ordinary instant form dynamics in the rest frame of the nucleus, whereas they are well satisfied when using instant form dynamics in the infinite-momentum frame, or using light-front form dynamics in an ordinary frame. Therefore a reliable theoretical treatment of deep inelastic lepton-nucleus scattering should be performed in the time-ordered perturbation theory in the infinite-momentum frame, or its equivalent, the light-cone perturbation theory in an ordinary frame. To this end, the authors extend the light-cone quantum field theory to the baryon-meson field to establish a relativistic composite model of nuclei. They then apply the impulse approximation to deep inelastic lepton-nucleus scattering in this model. As a first approximation, they consider only the nucleon degrees of freedom and neglect the Z-graph contributions. It is found that the results seem able to explain the EMC effect in trend but overestimate the ratio of the differential cross section for a bound nucleon to that for a free nucleon by about 8%. Some comparisons of the model with several relevant models are also presented.