EVIDENCE FOR K+ YIELDS P+ VV-.

The first observation of the decay K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}} has been reported. The E787 experiment presented evidence for the K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(K{sup +} {yields} {pi}{sup +}{nu}{ovr {nu}}) = 4.2{sub -3.5}{sup +9.7} x 10{sup -10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E7878 data sample, from the 1995-98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collected in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.