Self-Breaking of the Standard Model Gauge Symmetry

TL;DR

This work proposes that electroweak symmetry breaking and the Higgs boson can emerge from Standard Model gauge dynamics in TeV-scale extra dimensions, with the third generation propagating in the extra dimensions. Strong higher-dimensional gauge interactions generate bound states, notably a Higgs-like composite $H_U$, whose VEV triggers breaking and yields a large top Yukawa controlled by infrared fixed points, predicting $m_t \approx 174$ GeV and $M_h$ in the range $165$–$230$ GeV. The framework uses a NJL-like four-fermion approximation and power-law running above the compactification scale to connect high-energy compositeness with low-energy observables, while flavor symmetry breaking and comparisons with supersymmetry address phenomenological constraints. Overall, the model offers a predictive alternative to SUSY for EWSB, tying the light Higgs to the geometry of extra dimensions and the dynamics of gauge interactions, with testable collider implications.

Abstract

If the gauge fields of the Standard Model propagate in TeV-size extra dimensions, they rapidly become strongly coupled and can form scalar bound states of quarks and leptons. If the quarks and leptons of the third generation propagate in 6 or 8 dimensions, we argue that the most tightly bound scalar is a composite of top quarks, having the quantum numbers of the Higgs doublet and a large coupling to the top quark. In the case where the gauge bosons propagate in a bulk of a certain volume, this composite Higgs doublet can successfully trigger electroweak symmetry breaking. The mass of the top quark is correctly predicted to within 20%, without the need to add a fundamental Yukawa interaction, and the Higgs boson mass is predicted to lie in the range 165 - 230 GeV. In addition to the Higgs boson, there may be a few other scalar composites sufficiently light to be observed at upcoming collider experiments.

Figures (4)

• Figure 1: The predicted top mass as a function of the number of KK modes, $N_{\rm KK}$, and the compactification scale, $M_c$, in the six-dimensional theory with $n_g=1$.
• Figure 2: The predicted top mass as a function of $N_{\rm KK}$ and $M_c$ in the eight-dimensional theory with $n_g=1$.
• Figure 3: The predicted Higgs mass as a function of $N_{\rm KK}$ and $M_c$ in the six-dimensional theory with $n_g=1$. The shaded regions correspond to the top mass lying within 1--3 $\sigma$ (dark to light) of the experimental value, $174.3\pm 5.1$ GeV.
• Figure 4: The predicted Higgs mass as a function of $N_{\rm KK}$ and $M_c$ in the eight-dimensional theory. The shaded regions correspond to the top mass lying within 1--3 $\sigma$ (dark to light) of the experimental value.