Weak ΔS=1 scattering experiments: Are they needed and feasible?

We show that the reaction $K^{+}$p→${\pi }^{+}$p below the inelastic threshold for strong pion production is strongly dominated by the so-called penguin operators. An order-of-magnitude estimate based on the magnitude of the Fermi coupling constant leads to a cross section of about ${10}^{\mathrm{-}39}$ ${\mathrm{cm}}^2$. The enhancement discussed here increases this by two to three orders of magnitude. Thus, the study of this Δs=1 weak reaction can be a good probe of the interface between electroweak and strong interactions, and of our understanding of QCD dynamics.