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Dark Matter as the Trigger of Strong Electroweak Phase Transition

Talal Ahmed Chowdhury, Miha Nemevsek, Goran Senjanovic, Yue Zhang

Abstract

In this Letter, we propose a new possible connection between dark matter relic density and baryon asymmetry of the universe. The portal between standard model sector and dark matter not only controls the relic density and detections of dark matter, but also allows the dark matter to trigger the first order electroweak phase transition. We discuss systematically possible scalar dark matter candidates, starting from a real singlet to arbitrary high representations. We show that the simplest realization is provided by a doublet, and that strong first-order electroweak phase transition implies a lower bound on the dark matter direct detection rate. The mass of dark matter lies between 45 and 80 GeV, allowing for an appreciable invisible decay width of the Standard Model Higgs boson, which is constrained to be lighter than 130 GeV for the sake of the strong phase transition.

Dark Matter as the Trigger of Strong Electroweak Phase Transition

Abstract

In this Letter, we propose a new possible connection between dark matter relic density and baryon asymmetry of the universe. The portal between standard model sector and dark matter not only controls the relic density and detections of dark matter, but also allows the dark matter to trigger the first order electroweak phase transition. We discuss systematically possible scalar dark matter candidates, starting from a real singlet to arbitrary high representations. We show that the simplest realization is provided by a doublet, and that strong first-order electroweak phase transition implies a lower bound on the dark matter direct detection rate. The mass of dark matter lies between 45 and 80 GeV, allowing for an appreciable invisible decay width of the Standard Model Higgs boson, which is constrained to be lighter than 130 GeV for the sake of the strong phase transition.

Paper Structure

This paper contains 12 equations, 3 figures.

Figures (3)

  • Figure 1: Spin-independent direct detection cross section on nucleon plotted as a function of the DM mass. Colored regions represent DM relic density favored by WMAP, $\Omega_{\rm DM}h^2 \in (0.085, 0.139)$ at $3\sigma$, for positive (red) and negative (blue) $\lambda_S$. We have taken SM Higgs mass $m_h=120\,$GeV. The lower limit on the direct detection cross section from Xenon100 experiment is shown by the black solid line. Also shown in the figure are the dashed curves for constant $|\lambda_S|$.
  • Figure 2: Correlation between spin-independent direct detection cross section and the mass of the charged scalar, after imposing the strong electroweak transition condition $v_c/T_c>1$. We have scanned the parameter space: $m_h\in(115, 200)\,$GeV, $m_S\in(40, 80)\,$GeV, $m_A\in(100, 500)\,$GeV, $m_C\in(m_A-10\,{\rm GeV}, m_A+10\,{\rm GeV})$, $\lambda_S\in(0, 1)$ and $\lambda_D\in(0,3)$. We veto points where the thermal mass of $A$ or $C$ exceeds $1.8\, T_c$, which would invalidate the high temperature expansion.
  • Figure 3: Shape of the Higgs potential at the critical temperature and its dependence on different choices of parameters: DM self-interaction $\lambda_D$ (left panel) and SM Higgs boson mass $m_h$ (right panel). While varying $\lambda_D$, we have fixed $m_h=120\,$GeV, $m_S=60\,$GeV, $m_A=m_C=300\,$GeV and while varying $m_h$, we have fixed $\lambda_D=0$, $m_S=76\,$GeV, $m_A=m_C=300\,$GeV, respectively.