Testing Time Reversal Invariance with Cold Neutrons

CP violation is implemented in the Standard Model (SM) of particle physics via a non-trivial phase in the Cabbibo-Kobayashi-Maskava matrix 1. Dedicated experiments and facilities have been built to check the predictions of the SM for CP violation, e.g. in the Kaon or the B meson sectors. Up to now, no significant deviations have been found. However, the CP violation implemented in the SM is insufficient to explain the baryon-antibaryon asymmetry observed in the Universe 2. Therefore, new sources of CP violation are searched for in various systems. The neutron is well-suited to search for CP violation beyond the SM. The influence of the SM CP violation is so tiny that it will hardly ever be observed, whereas several scenarios beyond the SM permit observable effects. These effects can be searched for in properties of the neutron, namely in its electric dipole moment (EDM), or in triple correlations between the decay products. CP or T (time reversal) violation would become manifest in deviations of these values from 0. Therefore these effects would have an unambiguous experimental signature.