Direct tests of T, CP, CPT symmetries in transitions of neutral K mesons with the KLOE experiment

Tests of the T, CP and CPT symmetries in the neutral kaon system are performed by the direct comparison of the probabilities of a kaon transition process to its symmetry-conjugate. The exchange of in and out states required for a genuine test involving an antiunitary transformation implied by time-reversal is implemented exploiting the entanglement of K 0 K ‾ 0 pairs produced at a ϕ-factory. A data sample collected by the KLOE experiment at DAΦNE corresponding to an integrated luminosity of about 1.7 fb−1 is analysed to study the Δt distributions of the ϕ → K S K L → π + π − π ± e ∓ ν and ϕ → K S K L → π ± e ∓ ν 3 π 0 processes, with Δt the difference of the kaon decay times. A comparison of the measured Δt distributions in the asymptotic region Δ t ≫ τ S allows to test for the first time T and CPT symmetries in kaon transitions with a precision of few percent, and to observe CP violation with this novel method.