Violation of time reversal invariance in the decays KL→π+π-γ and KL→π+π-e+e-

The origin of the large CP-odd and T-odd asymmetry observed in the decay K-L --> pi(+)pi(-)e(+)e(-) is traced to the polarization properties of the photon in the; decay K-L - pi(+)pi(-)gamma. The Stokes vector of the photon (S)over right arrow = (S-1,S-2,S-3) is studied as a function of the photon energy and found to possess CP-violating components S-1 and S-2 which are large, despite being proportional to the epsilon parameter of the K-L wave function. The component S-1 is T-even and manifests itself as a circular polarization of the photon, while S-1 is T-odd and gives rise to the asymmetry observed in K-L --> pi(+)pi(-)e(+)e(-) . The latter survives in the limit in which all unitarity phases are absent,:and represents a genuine example of time reversal symmetry breaking in a CPT invariant theory.