Effects of Superheavy Quarks and Leptons in Low-Energy Weak Processes KL-> Formula, K+-> + Formula and K0 Formula0

Abstract

We investigate potentially important effects due to the existence of superheavy quarks and leptons of the sequential type in higher-order weak processes at low energies. The second-order {Delta}S[!=]0 neutral-current processes KL[->]{micro}[IMG]f1.gif" ALT="Formula" BORDER="0">, K+[->]{pi}+{nu}[IMG]f2.gif" ALT="Formula" BORDER="0"> and KL-KS mass difference are analysed allowing for fermions of masses comparable to or larger than the weak-boson mass in the Kobayashi-Maskawa scheme and in the general sequential scheme with an arbitrary number of generations. Possible connection between heavy-quark masses and light-heavy quark mixing are also examined. The requirement that the rare decay processes such as KL[->]{micro}[IMG]f1.gif" ALT="Formula" BORDER="0"> and K+[->]{pi}+{nu}[IMG]f2.gif" ALT="Formula" BORDER="0"> be absent up to order GF yields a rather stringent bound on the magnitude of light-heavy quark mixing: Such mixing has to be less than mW/mQuark times a factor much smaller than unity.