A New Measurement of the Rare Decay $K^{+}\to \ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$

Abstract

More than 400 $K^{+}\to \ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ events were observed in a rare $K^{+}$ decay experiment at the AGS. Normalized to the $K^{+}\to \ddot{I}{€}^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ decay, the branching ratio is determined to be $(9.22\pm 0.60(stat)\pm 0.49(syst))\times 10^{-8}$. This branching ratio and the $\hat{I}¼\hat{I}¼$ mass spectrum is in very good agreement with the measurement of the $K^{+}\to \ddot{I}{€}^{+}{e}^{+}{e}^{-}$ decay, but deviates significantly from the previous measurement.

4 pages, 6 figures in 7 eps files. Paper to be submitted to Phys Rev Lett