Phenomenology of Electroweak Symmetry Breaking from Theory Space

TL;DR

The paper develops theory-space (moose) constructions to realize electroweak symmetry breaking without supersymmetry, yielding naturally light Higgs bosons and perturbative TeV-scale new physics. It shows that a large top Yukawa can drive EWSB through calculable radiative corrections while collective symmetry breaking cancels one-loop quadratic divergences, making the Higgs sector natural up to a higher cutoff $\Lambda \sim 4\pi f$ with UV completion near $10$–$100$ TeV. The model predicts at least two light Higgs doublets, extra weak triplet/singlet scalars, and a stable dark-matter candidate from a geometric $\mathbb{Z}_4$ symmetry, plus a rich TeV-scale spectrum of heavy states that cancel divergences and modify collider phenomenology. The explicit $N=2$ torus realization provides concrete spectrum and coupling patterns, illustrating the mechanism and highlighting potential collider and cosmological implications as well as comparisons to supersymmetric approaches.

Abstract

Recently, a new class of realistic models for electroweak symmetry breaking have been constructed, without supersymmetry. These theories have naturally light Higgs bosons and perturbative new physics at the TeV scale. We describe these models in detail, and show that electroweak symmetry breaking can be triggered by a large top quark Yukawa coupling. A rich spectrum of particles is predicted, with a pair of light Higgs doublets accompanied by new light weak triplet and singlet scalars. The lightest of these new scalars is charged under a geometric discrete symmetry and is therefore stable, providing a new candidate for WIMP dark matter. At TeV energies, a plethora of new heavy scalars, gauge bosons and fermions are revealed, with distinctive quantum numbers and decay modes.

Figures (6)

• Figure 1: Theory space for the 4 $\times$ 4 torus. Sites $(-2,m)$ and $(2,m)$ are identified as are $(n,-2)$ and $(n,2)$. The thick arrows represent the link fields.
• Figure 2: Representation of top quark Lagrangian
• Figure 3: Moose diagrams for the $N=2$ torus. b) is an unfolding of a). There are 4 independent sites: in b), any two sites related by a reflection through the vertical or the horizontal axis are identified. An example of this identification is shown by the dotted arrows. There are 8 independent link fields represented by the thick arrows. a) shows clearly the sites and links while b) makes the plaquettes and all the discrete symmetries apparent.
• Figure 4: Ooperators ${\cal O}$, ${\cal O}'$,${\cal O}_8$ and ${\cal O}_8'$ included in the $N=2$ torus Lagrangian. They consist of a product of links forming a closed path. The links included in the product are represented by the arrows, and the large base indicates a trace should be included before the corresponding link. The $T_8$ indicates that a $T_8$ matrix should be inserted in the product. The final $\mathbb{Z}_4$ invariant operators are obtained by summing over the $90^{\circ}$ rotations of these pictures. e) is an example of this notation relevant for ${\cal O}_8$.
• Figure 5: Operators ${\cal O}_2$and ${\cal O}^8_2$ can be generated by the plaquette. Again, they are gauge invariant products of the links represented by arrows, the large base representing a trace and they are implicitly symmetrized by $90^{\circ}$ rotations.