Baryogenesis in the Two-Higgs Doublet Model

TL;DR

This work investigates electroweak baryogenesis in the CP-violating two-Higgs doublet model by analyzing the finite-temperature Higgs potential and bubble-wall dynamics. Using a one-loop effective potential and WKB transport equations for top quarks, they show that a strong first-order phase transition occurs for heavy extra Higgs masses ($m_H \gtrsim 300$ GeV) with the light Higgs allowed up to ~200 GeV, and that the generated baryon asymmetry can match the observed value. The CP-violating phase in the Higgs sector also generates electric dipole moments; EDM predictions typically lie below current bounds but are within reach of next-generation experiments, providing a crucial test of the scenario. Overall, the paper demonstrates a viable region of parameter space for EWBG in the 2HDM and discusses experimental implications for collider Higgs phenomenology and EDM searches.

Abstract

We consider the generation of the baryon asymmetry in the two-Higgs doublet model. Investigating the thermal potential in the presence of CP violation, as relevant for baryogenesis, we find a strong first-order phase transition if the extra Higgs states are heavier than about 300 GeV. The mass of the lightest Higgs can be as large as about 200 GeV. We compute the bubble wall properties, including the profile of the relative complex phase between the two Higgs vevs. The baryon asymmetry is generated by top transport, which we treat in the WKB approximation. We find a baryon asymmetry consistent with observations. The neutron electric dipole moment is predicted to be larger than about 10^{-27}ecm and can reach the current experimental bound. Low values of tanβare favored.

Figures (6)

• Figure 1: Lines of constant $\xi$ and $L_{\rm w}$ in the $m_h$-$m_{ H}$-plane for $\mu_3^2=10000~\hbox{GeV}^2$ and $\phi=0$. In addition, the line of the relative size of the one-loop corrections $\Delta=\max|\delta\lambda_i/\lambda_i|=0.5$ is shown. The Higgs masses are given in units of GeV.
• Figure 3: The same plot as in figs. \ref{['fig_10000_0.0001']} and \ref{['fig_10000_0.2']}, but for $\mu_3^2=20000~\hbox{GeV}^2$ and $\phi=0.2$
• Figure 4: The phase $\theta$ and the difference $\Delta\theta$ for the set $\mu_3^2=10000~\hbox{GeV}^2$, $\phi=0.2$. (a) The change of $\theta$ during the PT, as a function of $h_1$ (given in GeV), at fixed $m_h=150\;\hbox{GeV}$, $m_H=350\;\hbox{GeV}$. (b) $\Delta\theta$ versus $m_h$ (given in GeV) for $m_H=330\;\hbox{GeV}$ (solid) and $400\;\hbox{GeV}$ (dashed).
• Figure 5: Lines of constant neutron (solid) and electron EDMs (dashed) for the set $\mu_3^2=10000\;\hbox{GeV}^2$, $\phi=0.2$, $d_{n}$ is given in units of $10^{-26}\;e\,{\rm cm}$, $d_{e}$ in units of $10^{-27}\;e\,{\rm cm}$, and Higgs masses in GeV. The lower dotted line indicates the bound $\xi=1$, the upper one $L_{\rm w}=2$.
• Figure 6: The solid line represents $\eta_B$ as a function of the wall velocity for $m_h=125$ GeV, $m_H=350$ GeV, $\mu_3^2=10000~\hbox{GeV}^2$ and $\phi=0.2$. This parameter setting determines $L_{\rm w}=4.5/T$ and $\xi=1.6$. The dashed line would be the asymmetry when we substitute $E_{0z}\rightarrow E_0$ in the dispersion relations. The dotted curve corresponds to the case where the $W$-scatterings are in equilibrium.