Patterns of Flavour Violation in a Warped Extra Dimensional Model with Custodial Protection

TL;DR

This paper explores a warped extra dimensional model with custodial symmetry that suppresses certain Z boson couplings, analyzing its effects on rare meson decays and identifying distinctive experimental signatures.

Contribution

It provides a comprehensive analysis of rare K and B meson decays within a specific warped extra dimensional model, highlighting new tree-level Z boson contributions and their experimental implications.

Findings

Dominant new physics contribution from tree-level Z exchange.

Correlations between branching ratios and mixing observables.

Model can be distinguished from the Standard Model through specific decay patterns.

Abstract

We present a particular warped extra dimensional model, where the flavour diagonal and flavour non-diagonal Z boson couplings to left-handed down quarks are protected by the custodial symmetry P_LR. After a brief introduction of the model and of its main theoretical motivations, we present a complete study of rare K and B meson decays, including K+ --> pi+ nu anti-nu, K_L --> pi0 nu anti-nu, B_{s,d} --> mu+ mu- and B_{s,d} --> X_{s,d} nu anti-nu. In particular we restrict the parameter space of the model to the subspace which fits all quark masses, CKM mixing parameters and all the measured Delta F=2 observables, keeping the Kaluza-Klein scale in the reach of LHC (~(2-3)TeV). There we show that, in addition to the one loop contribution of the Standard Model (SM), the dominating new physics contribution to the rare decays of K and B_{s,d} mesons is the tree level exchange of the Z boson of the SM governed by right-handed couplings to down-type quarks. In order to reduce the parameter dependence, we study correlations between various branching ratios of B and K mesons and between Delta F=1 and Delta F=2 observables. The patterns that we find allow to distinguish this new physics scenario from the SM and can offer an opportunity to future experiments to confirm or rule out the model.