Further search for the decay K+-->pi(+)nunu;

Phys Rev Lett. 2000 Apr 24;84(17):3768-70. doi: 10.1103/PhysRevLett.84.3768.

Abstract

A search for additional evidence for the rare kaon decay K+-->pi(+)nunu; 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<229 MeV/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+-->pi(+)nunu;) = 1.5(+3.4)(-1.2)x10(-10).