Further evidence for the decay K+ -->pi+nu(nu)

Phys Rev Lett. 2002 Jan 28;88(4):041803. doi: 10.1103/PhysRevLett.88.041803. Epub 2002 Jan 11.

Abstract

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 contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).