Electroweak Symmetry Breaking and the Higgs Boson: Confronting Theories at Colliders

TL;DR

The paper develops a robust, model-independent EFT framework to confront electroweak symmetry breaking theories with LHC data, focusing on composite PNGB Higgs and SUSY realizations. By mapping collider measurements onto a and c-type Higgs couplings and employing CCWZ-based composite-Higgs formalism, it demonstrates how tree- and loop-level observables constrain extended EWSB sectors and the scales of new physics. It details methods to reconstruct and use Higgs likelihoods from various channels and precision tests, then applies these methods to case studies in warped/composite models and SUSY, illustrating current constraints and potential signatures in both tree- and loop-induced Higgs couplings. Overall, the analysis finds the Higgs properties so far consistent with SM predictions, though precise loop-level measurements remain a promising probe of naturalness and BSM dynamics, with the framework guiding future explorations at colliders.

Abstract

In this review, we discuss methods of parsing direct and indirect information from collider experiments regarding the Higgs boson and describe simple ways in which experimental likelihoods can be consistently reconstructed and interfaced with model predictions in pertinent parameter spaces. Ultimately these methods are used to constrain a five-dimensional parameter space describing a model-independent framework for electroweak symmetry breaking. We review prevalent scenarios for extending the electroweak symmetry breaking sector relative to the Standard Model and emphasize their predictions for nonstandard Higgs phenomenology that could be observed in LHC data if naturalness is realized in particular ways. Specifically we identify how measurements of Higgs couplings can be used to imply the existence of new physics at particular scales within various contexts, highlighting some parameter spaces of interest in order to give examples of how the data surrounding the new state can most effectively be used to constrain specific models of weak scale physics.

Figures (12)

• Figure 1: Dominant single-Higgs production from $\mathcal{O} (p^2)$ terms of Eq. (\ref{['eq:general']}). Gluon fusion at this level is rescaled by $c^2$ compared to the SM, VBF and VH by $a^2$.
• Figure 2: Illustration of vacuum misalignment and spontaneous breaking of gauged directions of $H$ induced from a rotation of $\phi_0$, by angle $\vartheta$ along a VEVed direction of the Goldstone space $G/H$.
• Figure 3: LHC likelihoods for Minimal Composite Higgs models and total combination including Tevatron data. Any preference for deviations from the SM would come with the implication of a very high scale for the strong dynamics.
• Figure 4: Breakdown and combination of all final states participating in the global fit. Individual contours are shown at 95% CL and the combination is shown at 68% and 95%. Shown separately as a yellow dashed contour we illustrate the combination including the effects of precision electroweak measurements after marginalizing over $U$ as discussed in appendix \ref{['sec:Data']}.
• Figure 5: Two conspiring effects in Higgs couplings to unbroken gauge directions coming from Higgs mixing of elementary and composite fermions. Left: Wavefunction renormalization from integrating out heavy fields (bold lines), leading to modification of the light field's Yukawa coupling. Right: Direct loop contribution from the heavy fields.