  One of the important issues of Quantum Chromodynamics (QCD) - the fundamental
theory of strong interaction, is the understanding of the role of the
quark-gluon interactions in the processes involving nuclear targets. One
direction in such studies is to explore the onset of the quark gluon degrees of
freedom in nuclear dynamics. The other direction is using the nuclear targets
as a `micro-labs' in studies of the QCD processes involving protons and
neutrons bound in the nucleus. In the proposed research, we work in both
directions considering high energy photo- and electro-production reactions
involving deuteron and $^3$He nuclei.
  In the first half of the research, we study the high energy break-up of the
$^3$He nucleus, caused by a incoming photon, into a proton-deuteron pair at the
large center of mass scattering angle. The main motivation of the research is
the theoretical interpretation of recent experimental data which revealed the
unprecedentedly large exponent $s^{-17}$, for the energy dependence of the
differential cross section. In the present research, we extend the theoretical
formalism of the hard QCD rescattering model to calculate energy and angular
dependences of the absolute cross section of the $\gamma ^3\text{He}\rightarrow
pd$ reaction in high momentum transfer limit.
  The second half of the research explores the deep-inelastic scattering of a
polarized electron off the polarized deuteron and $^3$He nuclei, to explore the
quark-gluon structure of polarized neutron. In this work, we developed a
comprehensive theoretical framework for calculation of the all relevant nuclear
effects that will allow the accurate extraction of the neutron data from
deep-inelastic scattering involving deuteron and $^3$He targets.

Nuclear Theory