Further search for the decay K+→π+ν¯ν

A search for additional evidence for the rare kaon decay K+→π+ν¯ν has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event. No new events were found in the pion momentum region examined, 211<P<229MeV/c. Including a reanalysis of the original data set, the backgrounds were estimated to contribute 0.08±0.02 events. Based on one observed event, the new branching ratio is B(K+→π+ν¯ν)=1.5^+3.4 _−1.2×10⁻¹⁰.