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Light asymmetric dark matter from new strong dynamics

Mads T. Frandsen, Subir Sarkar, Kai Schmidt-Hoberg

TL;DR

This work develops a mechanism to generate light asymmetric dark matter via two-scale strong dynamics linked to dynamical electroweak symmetry breaking. By introducing S1 and S2 sectors with scales $\Lambda_1$ and $\Lambda_2$ and a shared global $U(1)_{\mathrm{TB}}$, it shows how a dark baryon–like state and a GeV-scale ADM $\chi$ can inherit a common asymmetry through sphaleron processes, yielding $\Omega_\chi$ compatible with $\Omega_B$ through $\Omega_\chi = \frac{m_\chi \mathcal{N}_\chi}{m_B \mathcal{N}_B}\,\Omega_B$, with $m_\chi \approx 5$ GeV. Scale separation $\Lambda_1/\Lambda_2$ can be large, aided by four-fermion (gauged-NJL) interactions that lower the critical coupling $\alpha_c$ and extend the conformal window, enabling substantial separation while breaking EW at the correct scale. The model predicts testable phenomenology, including sizable self-interactions and potentially detectable spin-independent scattering cross-sections $\sigma \sim g_\chi^2 g_q^2 \frac{\mu^2}{m^4}$ for mediators with $m \sim 5$–$15$ GeV and $g_q \sim \Lambda_2/\Lambda_1 \lesssim 10^{-4}$, offering avenues for direct detection and collider signals from the technicolor sector.

Abstract

A ~5 GeV `dark baryon' with a cosmic asymmetry similar to that of baryons is a natural candidate for the dark matter. We study the possibility of generating such a state through dynamical electroweak symmetry breaking, and show that it can share the relic baryon asymmetry via sphaleron interactions, even though it has no electroweak interactions. The scattering cross-section on nucleons, estimated in analogy to QCD, is within reach of underground direct detection experiments.

Light asymmetric dark matter from new strong dynamics

TL;DR

This work develops a mechanism to generate light asymmetric dark matter via two-scale strong dynamics linked to dynamical electroweak symmetry breaking. By introducing S1 and S2 sectors with scales and and a shared global , it shows how a dark baryon–like state and a GeV-scale ADM can inherit a common asymmetry through sphaleron processes, yielding compatible with through , with GeV. Scale separation can be large, aided by four-fermion (gauged-NJL) interactions that lower the critical coupling and extend the conformal window, enabling substantial separation while breaking EW at the correct scale. The model predicts testable phenomenology, including sizable self-interactions and potentially detectable spin-independent scattering cross-sections for mediators with – GeV and , offering avenues for direct detection and collider signals from the technicolor sector.

Abstract

A ~5 GeV `dark baryon' with a cosmic asymmetry similar to that of baryons is a natural candidate for the dark matter. We study the possibility of generating such a state through dynamical electroweak symmetry breaking, and show that it can share the relic baryon asymmetry via sphaleron interactions, even though it has no electroweak interactions. The scattering cross-section on nucleons, estimated in analogy to QCD, is within reach of underground direct detection experiments.

Paper Structure

This paper contains 3 sections, 9 equations, 2 figures.

Table of Contents

  1. Asymmetric dark matter
  2. Two scales from a strongly interacting theory
  3. Phenomenology

Figures (2)

  • Figure 1: Upper panel: The conformal window for $SU(N_\mathrm{C})$ gauge theories with $N_2(F)$ fermions in the fundamental representation ($\mathcal{R}_2=F$), and 2 flavours in the (top to bottom): fundamental (dark blue), two-index antisymmetric (light blue), two-index symmetric (red), and adjoint (green) representations. Lower panel: The corresponding scale separation using the value of $N_2(F)$ at the lower boundary of the corresponding conformal window for the: two-index antisymmetric (blue dotted), adjoint (green dashed), and two-index symmetric (red solid) representations.
  • Figure 2: As in Fig. \ref{['fig1']}, but now as a function of $g_1$ (\ref{['NJLcomeon']}). Here the fundamental and antisymmetric representations are identical.