  We derive the parity- and time-reversal-violating nuclear interactions
stemming from the QCD theta term and quark/gluon operators of effective
dimension 6: quark electric dipole moments, quark and gluon chromo-electric
dipole moments, and two four-quark operators. We work in the framework of
two-flavor chiral perturbation theory, where a systematic expansion is
possible. The different chiral-transformation properties of the sources of
time-reversal violation lead to different hadronic interactions. For all
sources considered the leading-order potential involves known one-pion
exchange, but its specific form and the relative importance of short-range
interactions depend on the source. For the theta term, the leading potential is
solely given by one-pion exchange, which does not contribute to the deuteron
electric dipole moment. In subleading order, a new two-pion-exchange potential
is obtained. Its short-range component is indistinguishable from one of two
undetermined contact interactions that appear at the same order and represent
effects of heavier mesons and other short-range QCD dynamics. One-pion-exchange
corrections at this order are discussed as well.
