Contribution of CPLEAR to the physics of the neutral-kaon system

Abstract

We report the results of the CPLEAR experiment on CP-, T-, and CPT-symmetries in the neutral kaon system. CP-violation parameters are given for the K 0, K 0 → 2π, 3π decay channels. For the first time, T-violation is measured by a direct method using semileptonic decays. The CPT symmetry is tested through the parameters Im(δ) with a precision of 10 −5 and Re(δ) with a precision of a few 10 −4. With these two measurements, the difference in mass and width of K 0 and K 0 are bound to within 10 −18 GeV. In the limit of CPT invariance in the neutral kaon decays, the K 0 and K 0 masses are equal within 10 −19 GeV.