Flavour violating charged lepton decays in Little Randall-Sundrum Model

TL;DR

This paper investigates flavour violating charged lepton decays within the Little Randall-Sundrum model, showing how constraints from these decays limit the model's parameters and exploring ways to relax these bounds.

Contribution

It provides a detailed analysis of flavour violating processes in Little RS, including the impact of electroweak sector extensions and brane kinetic terms on experimental constraints.

Findings

$ ext{Br}( au ightarrow ext{three leptons})$ constraints are significant.

$ ext{Br}( ext{muon to electron conversion})$ imposes the strongest limit on KK gauge boson mass.

Inclusion of Brane Localised Kinetic Terms relaxes the KK mass bound from 30.7 TeV to 12 TeV.

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 \rightarrow e e e $, $\tau \rightarrow e e e $, $\tau \rightarrow \mu \mu \mu $, $\tau \rightarrow \mu e e $, $\tau \rightarrow e \mu \mu $ , $\mu \rightarrow e \gamma $, and $\mu Ti \rightarrow e Ti $. And we show that the dominant constraint arises from the $\mu Ti \rightarrow e Ti$ process which strongly limits the KK-1 gauge boson mass ($M_{KK}$) to be $\gtrsim 30.7 TeV $. We then derive and show that generalising the electro-weak gauge sector to include the Brane Localised Kinetic Term (BLKT) relaxes this constraint to $\gtrsim 12 TeV$. 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.