in the deep subthreshold region. The corresponding uncertainty in the binding energy then amounts to $\approx 30$ MeV. As indicated by few body calculations of Ref. [@WEI06] this problem strongly affects the outcome. The uncertainties of $f_{KN}$ require further coherent experimental and theoretical studies of KN and K-few-N interactions. It becomes one of the most important purposes of the K meson physics.

On the other hand, there is one consequence of Eq.(\[1\]) which is model independent. If the binding and recoil are so large the $f_{KN}$ amplitudes involve the energies below the thresholds of meson-hyperon decay channels. As a consequence the dominant decay modes are blocked and the lifetimes of nuclear K meson systems are determined only by multi-nucleon captures. This leads to the expectation that such states may live long enough to be detectable, [@WYC86].

There exists several calculations of KNN binding energies. These states are named K$^{-}$pp although in reality they correspond to isospin $I_{NN}=1 $ and total isospin $I_{tot}=1/2$. The first prediction by Akaishi and Yamazaki lead to $( E_B, \Gamma) =
(48,60) $ MeV [@AKA02]. With a similar, molecular type method, Dote and Weise [@DOT07] obtain $ E_B, < 50 $ MeV and indicate a strong 