Little Randall-Sundrum models:ϵKstrikes again

A detailed phenomenological analysis of neutral kaon mixing in ``little Randall-Sundrum'' models is presented. It is shown that the constraints arising from the $CP$-violating quantity ${ϵ}_{K}$ can, depending on the value of the ultraviolet cutoff, be even stronger than in the original Randall-Sundrum scenario addressing the hierarchy problem up to the Planck scale. The origin of the enhancement is explained, and a bound ${\ensuremath{\Lambda}}_{\mathrm{UV}}g\mathrm{\text{several}}$ ${10}^{3}\text{ }\text{ }\mathrm{TeV}$ is derived, below which vast corrections to ${ϵ}_{K}$ are generically unavoidable. Implications for nonstandard ${Z}^{0}\ensuremath{\rightarrow}b\overline{b}$ couplings ar…