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Towards Working Technicolor: Effective Theories and Dark Matter

Sven Bjarke Gudnason, Chris Kouvaris, Francesco Sannino

TL;DR

This work investigates dynamical electroweak symmetry breaking via a walking technicolor sector based on an $SU(2)$ gauge theory with two adjoint technifermions, near-conformal and compatible with precision constraints. It develops both linear and non-linear low-energy effective theories that encode the $SU(4) ightarrow SO(4)$ symmetry breaking and yield predictions for LHC/LC phenomenology, including a light composite Higgs near the electroweak scale. The study identifies a neutral technibaryon/neutral pseudo-Goldstone boson as a natural dark matter candidate, showing that, for TeV-scale masses and plausible thermal histories with sphaleron processes, this component can account for the observed dark matter density without fine-tuning. Overall, the EFT framework provides concrete collider-signature predictions and supports a viable dark matter scenario within a strongly coupled electroweak breaking sector.

Abstract

A fifth force, of technicolor type, responsible for breaking the electroweak theory is an intriguing extension of the Standard Model. Recently new theories have been shown to feature walking dynamics for a very low number of techniflavors and are not ruled out by electroweak precision measurements. We identify the light degrees of freedom and construct the associated low energy effective theories. These can be used to study signatures and relevant processes in current and future experiments. In our theory the technibaryons are pseudo Goldstone bosons and their masses arise via extended technicolor interactions. There are hypercharge assignments for the techniquarks which renders one of the technibaryons electrically neutral. We investigate the cosmological implications of this scenario and provide a component of dark matter.

Towards Working Technicolor: Effective Theories and Dark Matter

TL;DR

This work investigates dynamical electroweak symmetry breaking via a walking technicolor sector based on an gauge theory with two adjoint technifermions, near-conformal and compatible with precision constraints. It develops both linear and non-linear low-energy effective theories that encode the symmetry breaking and yield predictions for LHC/LC phenomenology, including a light composite Higgs near the electroweak scale. The study identifies a neutral technibaryon/neutral pseudo-Goldstone boson as a natural dark matter candidate, showing that, for TeV-scale masses and plausible thermal histories with sphaleron processes, this component can account for the observed dark matter density without fine-tuning. Overall, the EFT framework provides concrete collider-signature predictions and supports a viable dark matter scenario within a strongly coupled electroweak breaking sector.

Abstract

A fifth force, of technicolor type, responsible for breaking the electroweak theory is an intriguing extension of the Standard Model. Recently new theories have been shown to feature walking dynamics for a very low number of techniflavors and are not ruled out by electroweak precision measurements. We identify the light degrees of freedom and construct the associated low energy effective theories. These can be used to study signatures and relevant processes in current and future experiments. In our theory the technibaryons are pseudo Goldstone bosons and their masses arise via extended technicolor interactions. There are hypercharge assignments for the techniquarks which renders one of the technibaryons electrically neutral. We investigate the cosmological implications of this scenario and provide a component of dark matter.

Paper Structure

This paper contains 8 sections, 41 equations, 1 figure.

Table of Contents

  1. Introduction
  2. The Model
  3. Effective Theories
  4. The Linear Realization
  5. The Non-Linearly Realized Effective Theory
  6. The Dark-Side of the 5$^{\rm th}$ Force
  7. Conclusions
  8. Generators

Figures (1)

  • Figure 1: Using the values of the parameters indicated in the text: Left Panel: The fraction of technibaryon matter density over the baryonic one as function of the technibaryon mass. The desired value of $\Omega_{TB}/\Omega_{B} \sim 5$ depends on the lightest technibaryon mass and the value of $T^{\ast}$. Right Panel: By requiring the correct amount ($\Omega_{TB}/\Omega_{B} \sim 5$) of dark matter we show the relation between the technibaryon mass and $T^{\ast}$.