D. A. Roberts

A Limit on the branching ratio of K(L) ---> pi0 mu+ mu-

We report the results of a search for the decay K L →π 0 m + m - conducted by E799 at Fermilab. This decay mode is expected to have significant CP-violating contributions and a direct measurement could either confirm the standard model mechanisms for CP violation or point to physics beyond the standard model. No such events were seen. The 90% confidence level upper limit is determined to be B(K L →π 0 m + m - )<5.1×10 -9

Measurement of the branching ratio of K(L) ---> e+ e- gamma gamma

A new measurement of the [ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][gamma][gamma] branching ratio was carried out in Fermilab experiment E799. We observed 58 [ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][gamma][gamma] events. The measured branching ratio is [ital B]([ital K][sub [ital L]][r arrow][ital e][sup +][ital e][sup [minus]][gamma][gamma], [ital E][sub [gamma]][sup *][gt]5 MeV) = [6.5[plus minus]1.2 (stat) [plus minus]0.6 (syst)] [times]10[sup [minus]7].

Search for the decay K0(L) ---> pi0 pi0 gamma

We report the results of a search for the decay [ital K][sub [ital L]][sup 0][r arrow][pi][sup 0][pi][sup 0][gamma] conducted by the E799 Collaboration at Fermilab. The amplitude for this process vanishes to [ital O]([ital p][sup 4]) in chiral perturbation theory, so a measurement of the decay would directly probe [ital O]([ital p][sup 6]) effects. This is the first published search for this decay mode and we set a 90% confidence level upper limit on the branching ratio of [ital B]([ital K][sub [ital L]][sup 0][r arrow][pi][sup 0][pi][sup 0][gamma])[lt]2.3[times]10[sup [minus]4].