ANALYSIS OF THE DECAY K(L)-]PI(0)GAMMA-GAMMA AND EXPECTATIONS FOR THE DECAYS K(L)-]PI(0)E(+)E(-) AND K(L)-]PI(0)MU(+)MU(-)

A two-component model of the decay K(L) --> pi0gammagamma, in which the amplitude is the sum of a pion-loop contribution and a vector-meson-mediated term, is compared with data from the NA31 and E731 experiments. An estimate is obtained for the parameter G characterizing the strength of the vector-meson component. The amplitude of K(L)-->pi0gammagamma, determined in this way, is used to calculate the CP-conserving amplitude of the decays K(L)-->pi0e+e- and K(L)--> pi0mu+mu-, without neglect of lepton masses. This complex amplitude (containing both absorptive and dispersive parts) is allowed to interfere with the CP-violating amplitude expected from the short-distance interaction sdBAR --> l+l- and from the CP impurity of the K(L) wave function. Results are obtained for the branching ratios of K(L) --> pi0l+l- and for the CP-violating l+l- asymmetry in the Dalitz plot.