Symmetries and the NN interaction

Spin is a most important commodity which serves to test conservation laws and to measure symmetry violations to a high degree of accuracy. One cannot fail to note the high level of sophistication exhibited in current symmetry violation experiments involving spin. In many instances the objectives have not been restricted to verifying the extent of the validity of a conservation law or symmetry principle but to make inroads into understanding the short range hadronic interaction. The topics covered in this review are the following: charge symmetry breaking due to the so-called class IV interaction which preserves neither charge symmetry, nor charge independence, nor isospin (in neutron-proton scattering); parity violation in nuclear systems due to the flavor conserving weak hadronic interaction (in proton-proton scattering and in scattering of epithermal neutrons from nuclei); and Cp violation or time-reversal non invariance assuming Cpt invariance is maintained (in reactions like pp → ΛΛ-). Reference to related measurements and possible extensions are made. (author)