The Custodial Randall-Sundrum Model: From Precision Tests to Higgs Physics

TL;DR

This paper reexamines the custodial Randall-Sundrum model with an extended gauge symmetry, providing analytic formulas for low-energy spectrum and couplings, and presents a comprehensive one-loop analysis of Higgs physics at the LHC.

Contribution

It introduces a novel KK decomposition in the mass basis and offers the first complete one-loop Higgs production and decay calculations in this model.

Findings

Protection mechanisms for the T parameter and Z couplings are clarified.

No protection exists in the charged-current sector.

Complete Higgs boson production and decay analysis at one-loop level.

Abstract

We reexamine the Randall-Sundrum (RS) model with enlarged gauge symmetry SU(2)_L x SU(2)_R x U(1)_X x P_LR in the presence of a brane-localized Higgs sector. In contrast to the existing literature, we perform the Kaluza-Klein (KK) decomposition within the mass basis, which avoids the truncation of the KK towers. Expanding the low-energy spectrum as well as the gauge couplings in powers of the Higgs vacuum expectation value, we obtain analytic formulas which allow for a deep understanding of the model-specific protection mechanisms of the T parameter and the left-handed Z-boson couplings. In particular, in the latter case we explain which contributions escape protection and identify them with the irreducible sources of P_LR symmetry breaking. We furthermore show explicitly that no protection mechanism is present in the charged-current sector confirming existing model-independent findings. The main focus of the phenomenological part of our work is a detailed discussion of Higgs-boson couplings and their impact on physics at the CERN Large Hadron Collider. For the first time, a complete one-loop calculation of all relevant Higgs-boson production and decay channels is presented, incorporating the effects stemming from the extended electroweak gauge-boson and fermion sectors.