Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma

The KTeV E799 experiment has conducted a search for the rare decay K-L ->pi(0)pi(0)gamma via the topology K-L ->pi(0)pi(0)(D)gamma (where pi(0)(D)->gamma e(+)e(-)). Because of Bose statistics of the pi(0) pair and the real nature of the photon, the K-L ->pi(0)pi(0)gamma decay is restricted to proceed at lowest order by the CP conserving direct emission (DE) of an E2 electric quadrupole photon. The rate of this decay is interesting theoretically since chiral perturbation theory predicts that this process vanishes at level O(p(4)). Therefore, this mode probes chiral perturbation theory at O(p(6)). In this paper we report a determination of an upper limit of 2.43x10(-7) (90% CL) for K-L ->pi(0)pi(0)gamma. This is approximately a factor of 20 lower than previous results.