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 ${\Lambda }_{\mathrm{UV}}>\mathrm{\text{several}}$ ${10}^3\mathrm{TeV}$ is derived, below which vast corrections to ${ϵ}_K$ are generically unavoidable. Implications for nonstandard $Z^0\to b\overline{b}$ couplings are briefly discussed.

• Received 2 December 2008

DOI:https://doi.org/10.1103/PhysRevD.79.076001