Warped Extra Dimensions: Flavor, Precision Tests and Higgs Physics

TL;DR

This thesis explores the phenomenology of Randall-Sundrum models with various gauge symmetries, analyzing flavor-changing effects, Higgs physics, and compatibility with experimental anomalies, providing new insights into their collider signatures and flavor structure.

Contribution

It offers a comprehensive analysis of flavor effects, Higgs production, and decay in Randall-Sundrum models, including exact propagator expressions and one-loop calculations, advancing understanding of their collider phenomenology.

Findings

Randall-Sundrum models can improve agreement with certain flavor observables.

Higgs production and decay channels are sensitive to large new physics scales.

The t → cZ and t → ch decays could be observable at the LHC.

Abstract

In this thesis, the phenomenology of the Randall-Sundrum setup is investigated. In this context models with and without an enlarged SU(2)_L x SU(2)_R x U(1)_X x P_{LR} gauge symmetry, which removes corrections to the T parameter and to the Z b_L \bar b_L coupling, are compared with each other. The Kaluza-Klein decomposition is formulated within the mass basis, which allows for a clear understanding of various model-specific features. A complete discussion of tree-level flavor-changing effects is presented. Exact expressions for five dimensional propagators are derived, including Yukawa interactions that mediate flavor-off-diagonal transitions. The symmetry that reduces the corrections to the left-handed Z b \bar b coupling is analyzed in detail. In the literature, Randall-Sundrum models have been used to address the measured anomaly in the t \bar t forward-backward asymmetry. However, it will be shown that this is not possible within a natural approach to flavor. The rare decays t \to cZ and t \to ch are investigated, where in particular the latter could be observed at the LHC. A calculation of \Gamma_{12}^{B_s} in the presence of new physics is presented. It is shown that the Randall-Sundrum setup allows for an improved agreement with measurements of A_{SL}^s, S_{\psi\phi}, and \Delta\Gamma_s. For the first time, a complete one-loop calculation of all relevant Higgs-boson production and decay channels in the custodial Randall-Sundrum setup is performed, revealing a sensitivity to large new-physics scales at the LHC.