Time evolution of decay spectrum in K-0,(K-0)over-bar -> pi(+)pi(-)e(+)e(-)

We consider the decay K-0(K-0) --> pi(+) pi(-) e(+) e(-) of a neutral K mes on prepared in a state of strangeness +1(-1). The time evolution of the sta te produces remarkable time-dependent effects in the angular distribution o f 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)--> pi(+) pi(-) gamma. We study, in particular, the CP-odd, T-odd term in the d istribution 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, and discuss the case of K-S regene ration in a K-L beam. (C) 2000 Elsevier Science B.V. All rights reserved.