Phenomenology of Induced Electroweak Symmetry Breaking

TL;DR

This paper explores models of electroweak symmetry breaking driven by a tadpole mechanism involving an auxiliary Higgs sector, predicting altered Higgs couplings and rich phenomenology, with current constraints and future LHC sensitivities analyzed.

Contribution

It introduces a class of models where electroweak symmetry breaking is caused by a tadpole from an auxiliary Higgs sector, affecting Higgs couplings and phenomenology, and provides comprehensive experimental constraints and projections.

Findings

Higgs cubic coupling can be reduced to 0.4 times the SM value.

Current LHC data constrains these models but leaves significant parameter space open.

Upcoming 14 TeV LHC run will further test and potentially discover these models.

Abstract

We study the phenomenology of models of electroweak symmetry breaking where the Higgs potential is dominated by a positive quadratic term destabilized by a tadpole arising from the coupling to an "auxiliary" Higgs sector. The auxiliary Higgs sector can be either perturbative or strongly coupled, similar to technicolor models. Since electroweak symmetry breaking is driven by a tadpole, the cubic and quartic Higgs couplings can naturally be significantly smaller than their values in the standard model. The theoretical motivation for these models is that they can explain the 125 GeV Higgs mass in supersymmetry without fine-tuning. The auxiliary Higgs sector contains additional Higgs states that cannot decouple from standard model particles, so these models predict a rich phenomenology of Higgs physics beyond the standard model. In this paper we analyze a large number of direct and indirect constraints on these models. We present the current constraints after the 8 TeV run of the LHC, and give projections for the sensitivity of the upcoming 14 TeV run. We find that the strongest constraints come from the direct searches $A^0 \to Zh$, $A^0 \to t\bar{t}$, with weaker constraints from Higgs coupling fits. For strongly-coupled models, additional constraints come from $\rho^+ \to WZ$ where $\rho^+$ is a vector resonance. Our overall conclusion is that a significant parameter space for such models is currently open, allowing values of the Higgs cubic coupling down to 0.4 times the standard model value for weakly coupled models and vanishing cubic coupling for strongly coupled models. The upcoming 14 TeV run of the LHC will stringently test this scenario and we identify several new searches with discovery potential for this class of models.