Deuteron photodisintegration within the Bethe-Salpeter formalism: Effects of negative-energy components

Relativistic covariance requires that an analysis of the reaction γd → pn within a field-theoretical model of the nucleon-nucleon interaction involve negative-energy states. Relativistic effects and the contributions of negative-energy states in the Bethe-Salpeter amplitude to the differential cross section, the asymmetry of linearly polarized photons, and tensor asymmetries of the target deuteron are estimated on the basis of the Bethe-Salpeter formalism as applied to describing the interaction of an electromagnetic field with a two-nucleon system. It is found that the contribution of such states becomes sizable with increasing photon energy, but that it does not change the general qualitative behavior of observables as functions of angles.