Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to… (More)
This is a letter of intent for a new measurement of the branching ratio for the K + → π + ν ¯ ν decay with a low-energy DC-separated K + beam in the initial experimental hall  for the slow-extracted proton beams at J-PARC . With the established experimental methods using K + decays at rest and a solenoidal magnetic spectrometer, we observe more than… (More)
Recent results and future prospects of rare kaon-decay experiments at KEK, BNL, CERN and FNAL are reviewed. Topics include lepton flavor violation, T-violating transverse muon polarization in K + µ3 , exotic decays, K 0 → π 0 + − , and K → πνν.
Experiment E949 at Brookhaven National Laboratory studied the rare decay K ! and other processes with an exposure of 1:77 10 12 K 's. The data were analyzed using a blind analysis technique yielding one candidate event with an estimated background of 0:30 0:03 events. Combining this result with the observation of two candidate events by the… (More)
This is a Letter of Intent for a new experimental program in J-PARC, combining the topics of " Hadron Physics " and " Kaon Physics " by using the large solenoidal spectrometer of the BNL-E949 experiment and with a low-momentum DC-separated K + beam. The exotic Θ + baryon resonance at 1540 MeV/c 2 is studied with the reaction K + n → Θ + → K 0 p followed by… (More)