The CPLEAR results on T and CPT symmetries in the neutral-kaon system

We report the results of the CPLEAR experiment on T and CPT symmetries in the neutral-kaon system. CPLEAR has experimentally observed, for the first time, the violation of T invariance by a direct method using semileptonic decays. The CPT symmetry is tested via the parameter Re( delta ) with a precision of a few times 10/sup -4/ and Im( delta ), from the Bell-Steinberger relation, with a precision of a few times 10/sup -5/. This allows the mass and decay- width equalities between K/sup 0/ and K/sup 0/ to be tested down to the level of 10/sup -18/ GeV. (8 refs).