CPT symmetry and neutral kaons

Abstract

We discuss the accuracy of CPT invariance tests in the neutral kaon decays. The possible CPT non-invariance is parametrized by amplitudes of two types: (i) CP violating, but T conserving, and (ii) T violating, but CP conserving. It is shown that the experimental data are consistent with CPT symmetry essentially within two standard deviations. The source of this not quite satisfactory agreement is the experimental value of the phase φ00 of the ratio A(KL0→π0π0) A(KS0→π0π0), which differs by two standard deviations from the phase φ+- of the ratio A(KL0→π+π-) A(KS0→π+π-) decay amplitude. We argue that to get better agreement with CPT invariance, the value of the phase φ00 has to be equal to the value of the phase φ+- within the errors of the latter. New, more accurate measurements of the phase φ00 would be very interesting to rest CPT invariance, especially taking into account that neutral kaons allow the test with much better accuracy than any other particle. © 1984.