  We review recent progress in the theoretical description of the violation of
discrete space-time symmetries in hadronic and nuclear systems. We focus on
parity-violating and time-reversal-conserving interactions which are induced by
the Standard Model weak interaction, and on parity- and time-reversal-violating
interactions which can be caused by a nonzero QCD theta term or by
beyond-the-Standard Model physics. We discuss the origins of such interactions
and review the development of the chiral effective field theory extension that
includes discrete symmetry violations. We discuss the construction of
symmetry-violating chiral Lagrangians and nucleon-nucleon potentials and their
applications in few-body systems.
