J.R. Stone

Evidence for the decay K+ ---> pi+ neutrino anti-neutrino

An event consistent with the signature expected for the rare kaon decay K+ --> pi+ nu anti-nu has been observed. In the pion momentum region examined, 211 pi+ nu anti-nu, the branching ratio is (4.2 +9.7/-3.5) x E-10.

Further search for the decay K+ ---> pi+ nu anti-nu in the momentum region P < 195-MeV/c

We report the results of a search for the decay

Search for the decay in the momentum region Pπ<195 MeV/c

K^+ \to \pi^+ \nu \bar \nu

Search for the decay K+ ---> pi+ nu anti-nu in the momentum region P(pi) less than 195-MeV/c

in the kinematic region with

Search for the rare decay K+ ---> pi+ gamma

\pi^+

Further search for the decay K+ ---> pi+ neutrino anti-neutrino

momentum

Further Search for the DecayK+→π+νν¯

140<P<195

Evidence for the Decay K{sup +}{r_arrow}{pi}{sup +}{nu}{bar v}

MeV/c using the data collected by the E787 experiment at BNL. No events were observed. When combined with our previous search in this region, one candidate event with an expected background of

Evidence for the DecayK+→π+νν¯

1.22 \pm 0.24

Measurement of the K+ --> pi+ nu nu branching ratio

events results in a 90% C.L. upper limit of