Experimental searches for parity- and time reversal violations between hadrons

Tests that measure parity-violation (PV) and time-reversal invariance (TRI) are precision experiments. The challenge of these experiments is to find all relevant systematic error sources reduce the sensitivity of the experimental set-up with respect to these error sources, and finally measure and correct for the remaining effects. Therefore, especially null-tests, by which the difference from null of the observable in question reflects the amount the corresponding symmetry is violated, allow for an increased accuracy of the experimental result. Further improvements are achieved by utilizing inherent or artificially introduced correlations (usually) in the time-domain. It will be shown that under these conditions especially polarization observables qualify. In this context examples from the Bonn PV experiment are given and the implications for a novel TRI null-test are discussed. This T-odd, P-even TRI test measures the total cross-section asymmetry Ay,xz in proton- deuteron scattering, whereas the T-even, P-odd Bonn PV experiment measured the angle integrated longitudinal analyzing power Az in proton-proton scattering. For COSY-Juelich PV tests at 230 MeV and 1.5 GeV as well as this novel TRI test were proposed and accepted