Strong Dynamics and Electroweak Symmetry Breaking

TL;DR

The paper surveys strong-dynamics approaches to electroweak symmetry breaking, emphasizing Technicolor, Extended Technicolor, and top-quark–driven mechanisms (Topcolor, Top Seesaw) as viable alternatives to elementary Higgs descriptions. It details the theoretical structure, spectroscopy, and phenomenology of TC/ETC and related models, including walking/ multi-scale variants, and analyzes precision electroweak constraints (S,T,U) and collider signatures (WW/ZZ scattering, technirho production, PNGBs, colorons, Z' bosons). It also explores extensions incorporating SUSY, deconstructed extra dimensions, and Little Higgs ideas, highlighting how these frameworks can address flavor, FCNCs, and naturalness while remaining testable with current/future experiments. The review argues that NSD models can coexist with precision data and SUSY, and outlines concrete experimental channels at the Tevatron, LHC, and linear colliders to probe their rich spectra and dynamics. Overall, it presents a cohesive landscape where dynamical EWSB remains viable and experimentally accessible, contingent on specific model-building choices and spectrum arrangements.

Abstract

The breaking of the electroweak symmetry, and origin of the associated ``weak scale,'' may be due to a new strong interaction. Theoretical developments over the past decade have led to viable models and mechanisms that are consistent with current experimental data. Many of these schemes feature a privileged role for the top quark, and third generation, and are natural in the context of theories of extra space dimensions at the weak scale. We review various models and their phenomenological implications which will be subject to definitive tests in future collider runs at the Tevatron, the LHC, and future linear electron-positron colliders, as well as sensitive studies of rare processes.

Figures (78)

• Figure 1: The $(2N_D)^2-1$ Nambu-Goldstone bosons corresponding to an $N_D=2$ extension of the minimal model. The $\eta'_{T}$ corresponds to the unit matrix.
• Figure 2: Event yields at the LHC for $\rho_T \to W^\pm Z^0 \to \ell^\pm \nu_\ell \ell^+ \ell^-$ for $M_{\rho_T} = 1.0$, $2.5$ TeV; from Ref.Golden:1995xv. A conventional techni-$\rho$ resonance of mass much above 1 TeV would be invisible in the channel $\rho_T \to W^\pm Z^0 \to \ell^\pm \nu_\ell \ell^+ \ell^-$,.
• Figure 3: Vector Meson Dominance production of techni-$\rho$ with subsequent decay to $W^+Z$ in $pp$ collider with center-of-mass energies, $20$, $40$ and $100$ TeV (from EHLQ Eichten:1998kn).
• Figure 4: Vector Meson Dominance production of techni-$\rho$ with subsequent decay to $W^\pm Z$ in $pp$ collider with center-of-mass energies, $20$, $40$ and $100$ TeV (from EHLQ Eichten:1998kn).
• Figure 5: Differential cross section for production of $P^0{}'$ at $y=0$ in $pp$ and $p\bar{p}$ collisions with indicated center-of-mass energy in TeV (reproduced from EHLQ Eichten:1998kn).