Rare Kaon Decay From E949 At BNL: K^+ -->pi^+ nunubar

Abstract

In the first year of physics run, the E949 experiment at Brookhaven National Laboratory has already collected $1.8\times 10^{12}$ kaons stopping in the target. Additional evidence for the rare charged kaon decay $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ has been observed. Combined with previous results from the E787 experiment, the branching ratio is measured to be Br($K^{+}\to {\pi }^{+}\nu \bar{\nu }$)=$(1.47_{-0.89}^{+1.30})\times 10^{-10}$.

arXiv comment4pages. Submitted to 32nd International Conference on High-Energy Physics (ICHEP04), Beijing, China, 16-22 Aug 2004