Taming the $\epsilon_K$ in Little Randall Sundrum Models

TL;DR

This paper demonstrates that the constraints on Little Randall Sundrum models from Kaon physics can be significantly relaxed by introducing Brane Localised Kinetic Terms or flavor symmetries, potentially allowing lighter KK gluons detectable at the LHC.

Contribution

The study shows how Brane Localised Kinetic Terms and flavor symmetries can reduce the Kaon physics constraints on Little RS models, enabling lighter KK gluons.

Findings

Constraints on KK gluon mass can be lowered to 5 TeV.

Brane Localised Kinetic Terms modify KK gluon wave functions.

Flavor symmetries further relax Kaon physics constraints.

Abstract

The Randall Sundrum (RS) models receive significant constraints from the neutral Kaon system. The CP violating observable $\epsilon_K$, in Randall Sundrum scenario, requires the lightest KK gluon to be heavier than $\sim$ 24 TeV. The constraint is even stronger in the Little Randall Sundrum models (LRS), $\gtrsim$ 32 TeV. The LRS models are motivated for their possible visibility at the Large Hardon Collider (LHC). We show that the stringent constraints from K-physics can be relaxed in the LRS models, in the presence of the Brane Localised Kinetic Terms (BLKT). In particular, for a range of values, a UV BLKT could significantly modify the lightest KK gluon wave function such that the limit can reduces to 5 TeV. We also show that such a relaxation of the constraints can also be achieved by imposing flavour symmetries {\`a la } Minimal Flavour Protection.