Estimate of $B(K\to\pi\nu\overline{\nu})|_{SM}$ from Standard Model Fits to $\Lambda_{t}$

We estimate $B(\kzpnn)$ in the context of the Standard Model by fitting for \lamt $\equiv V_{td}V^*_{ts}$ of the `kaon unitarity triangle' relation. We fit data from \ek, the CP-violating parameter describing $K$-mixing, and \apsiks, the CP-violating asymmetry in \bpsiks decays. Our estimate is independent of the CKM matrix element \vcb and of the ratio of B-mixing frequencies \bsbd. The measured value of $B(\kpnn)$ can be compared both to this estimate and to predictions made from \bsbd.