  We consider the decay K^0 (K^0 bar) -> pi^+ pi^- e^+ e^- of a neutral K meson
prepared in a state of strangeness +1 (-1). The time evolution of the state
produces remarkable time-dependent effects in the angular distribution of the
pi^+ pi^- e^+ e^- system. These effects are correlated with the time-dependence
of the photon polarization in the radiative decay K^0 (K^0 bar) -> pi^+ pi^-
gamma. We study, in particular, the CP-odd, T-odd term in the distribution d
Gamma / d phi of the angle between the pi^+ pi^- and the e^+ e^- planes. We
also give the spectrum in the case that the decaying meson is an incoherent
mixture of K^0 and K^0 bar, and discuss the case of K_S regeneration in a K_L
beam.

High Energy Physics - Phenomenology