Flavour violating charged lepton decays in Little Randall-Sundrum Model

Abstract

The Little Randall-Sundrum (Little RS) model receives significantly stronger constraints from the flavour observables in comparison to Randall-Sundrum (RS) model. In this paper, we analyse the effect of the electro-weak sector in Little RS on flavour changing decays of charged leptons. We compare the predictions of the model with the current limits on the flavour violating Branching Ratios of $\mu \to eee$, $\tau \to eee$, $\tau \to \mu \mu \mu$, $\tau \to \mu ee$, $\tau \to e\mu \mu$ , $\mu \to e\gamma$, and $\mu Ti\to eTi$. And we show that the dominant constraint arises from the $\mu Ti\to eTi$ process which strongly limits the KK-1 gauge boson mass ($M_{KK}$) to be $\gtrsim 30.7TeV$. We then derive and show that generalising the electro-weak gauge sector to include the Brane Localised Kinetic Term (BLKT) relaxes this constraint to $\gtrsim 12TeV$. Towards the conclusion, we comment on the possibility that the large flavour violating currents can be mitigated by relaxing the assumption regarding the unnatural thinness and rigidity of the UV-brane and discuss the possibility of suppression of these currents in presence of fat fluctuating branes.

Comments: 12 pages, 7 figures, accepted to be published in prd