Experimental searches for CP and CPT symmetries violation in the neutral kaons system

The aim of this lecture is to give an overview of the experiments devoted to the study and research of CP, T and CPT symmetries invariance violations in the system of neutral K mesons. The discovery of K mesons has provided crucial informations for the elaboration of the standard model. However, the observation of CP violation has remained confined to the K system. The origin of the observed CP violation remains hypothetic. Its origin could be a complex phase in the mixing matrix of quarks. In the standard model of electroweak interactions, several evidences of the CP violation exist: the observed K neutral mesons (KL and KS) are not proper states of CP and are due to CP violation in the K0 - anti-K0 mixture. On the other hand, the model predicts also a CP violation in decay amplitudes, named direct CP violation. Important experiments have been carried out for its demonstration. The K system is also the most precise test for CPT invariance. A description of the experiments in progress developed to improve the precision of these tests is given. The plan of the lecture is the following: after a recall of K0 - anti-K0 phenomenology, some important steps in the CP violation study are described. Then, the regeneration phenomenon is briefly described and two of the most recent measurements of the direct CP violation parameter are analysed. Finally, the CPT invariance tests are described with their parameters and the measurements in progress. A review of the principal results is given in conclusion with their improvements expected in a near future. (J.S.). 71 refs., 4 figs., 4 tabs