Evidence for $K^+ \to π^+ ν\barν$
Abstract
Description
The first observation of the decay $K^+ \to π^+ ν\barν$ (pnn) has been reported. The E787 experiment presented evidence for this decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(pnn) = 4.2$^{+9.7}_{-3.5}\times10^{-10}$, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
10 pages with 3 figures. Contribution to the proceedings of the International Conference on CP-Violation in Kaons; Dec. 18--19, 1998; KEK-Tanashi, Tokyo, Japan
10 pages with 3 figures. Contribution to the proceedings of the International Conference on CP-Violation in Kaons; Dec. 18--19, 1998; KEK-Tanashi, Tokyo, Japan