  Relativistic effects and the role of heavy meson exchange in deuteron
photodisintegration are studied systematically for photon energies below the
pion production threshold. In a (p/M)-expansion, all leading order relativistic
one-body and pi-exchange as well as all static heavy meson exchange currents
consistent with the Bonn OBEPQ model are included. In addition, one- and
two-body boost effects have been investigated. Sizeable effects from the
various two-body contributions beyond pi-exchange have been found in almost
every observable considered, i.e., differential cross section and single
polarization observables.
