Results on CP, T, CPT symmetries with tagged K0andK0K^{0} and K^{0} by CPLEAR

We report the results of the CPLEAR experiment on CP-, T- and CPT- symmetries in the neutral kaon system. CPLEAR has experimentally determined, for the first time, the violation of T invariance by a direct method using semileptonic decays. The CPT symmetry is tested through the parameters re( delta ) with a precision of a few 10/sup -4/ and Im( delta ), from the Bell-Steinberger relation, with a precision of 10/sup -5/. This allows the mass equality between the K /sup 0/ and K/sup 0/ to be tested down to the level of 10/sup -19/ Ge V. (11 refs)