Studying discrete symmetry violation in neutron-nucleus systems

P-violation between nucleons resulting from the weak interaction is a valuable resource in the test of quantum chromodynamics (QCD). Few-body systems involving the neutron such as n+p, n+$^3$He, n+$4^$He and n+D may be used to determine parameters in effective field theories (EFT) which describe QCD in the non-perturbative limit. P-violation may appear as angular asymmetry of emitted particles or as P-odd spin rotation of neutrons transmitted through a nuclear target, and experiments to measure these observables with high sensitivity are in progress. 

Nucleon-nucleon (NN) P-violation also plays an important role in the search for T-violation using neutron-induced compound nuclear states. P-violation in the NN interaction may be enhanced by up to $10^6$ times in states such as $^{139}$La+n and $^{131}$Xe+n. T-violation may be enhanced by the same mechanism implying that a sensitive T-violation search might be possible using compound nuclei. Additionally, EFT parameters determined through measurements of P-violation are needed to estimate the sensitivity of a T-violation search. I will discuss experiments seeking to measure NN parity violation as well as a search for T-violation in compound nuclear systems.