DECAYS K(L,S)-]PI(0)PI(0)GAMMA AND K(L,S)-]PI(0)PI(0)E+E- AS PROBES OF CHIRAL DYNAMICS

The decays K(L,S) --> pi0pi0gamma are examples of quadrupole transitions (E2 and M2 respectively) which are forbidden in chiral perturbation theory (ChPT) at O(p4). At the same time, the virtual photon amplitude K(l) --> pi0pi0gamma* is calculable in ChPT. Using a plausible estimate for the real photon amplitude K(L) --> pi0pi0gamma, we show that the decay rate of K(L) --> pi0pi0e+e- contains comparable contributions from the E2 and virtual photon mechanisms, and that the two components can be clearly distinguished in the invariant mass spectrum of the e+e- pair.