  A relativistic and quantum mechanical framework to compute nuclear
transparencies for pion photo- and electroproduction reactions is presented.
Final-state interactions for the ejected pions and nucleons are implemented in
a relativistic eikonal approach. At sufficiently large ejectile energies, a
relativistic Glauber model can be adopted. At lower energies, the framework
possesses the flexibility to use relativistic optical potentials. The proposed
model can account for the color-transparency (CT) phenomenon and short-range
correlations (SRC) in the nucleus. Results are presented for kinematics
corresponding to completed and planned experiments at Jefferson Lab. The
influence of CT and SRC on the nuclear transparency is studied. Both the SRC
and CT mechanisms increase the nuclear transparency. The two mechanisms can be
clearly separated, though, as they exhibit a completely different dependence on
the hard scale parameter. The nucleon and pion transparencies as computed in
the relativistic Glauber approach are compared with optical-potential and
semi-classical calculations. The similarities in the trends and magnitudes of
the nuclear transparencies indicate that they are not subject to strong model
dependencies.
