Is electroweak baryogenesis dead?

Abstract

Electroweak baryogenesis is severely challenged in its traditional settings: the minimal supersymmetric standard model, and in more general two Higgs doublet models. Fine tuning of parameters is required, or large couplings leading to a Landau pole at scales just above the new physics introduced. The situation is somewhat better in models with a singlet scalar coupling to the Higgs so as to give a strongly first-order phase transition due to a tree-level barrier, but even in this case no UV complete models had been demonstrated to give successful baryogenesis. Here, we point out some directions that overcome this limitation, by introducing a new source of particle-antiparticle (CP) violation in the couplings of the singlet field. A model of electroweak baryogenesis requiring no fine tuning and consistent to scales far above 1 TeV is demonstrated, in which dark matter plays the leading role in creating a CP asymmetry that is the source of the baryon asymmetry.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'.

Keywords: dark matter; electroweak baryogenesis; electroweak phase transition.

Figure 1.

(a) The essential ingredients of electroweak baryogenesis, surrounding a bubble nucleated during a first-order electroweak phase transition. (b) Evolution of the Higgs potential with temperature for a second- or first-order phase transition.

Figure 2.

(a) MSSM contribution to Higgs production at hadron colliders via gluon fusion with light (right-handed top squark) in the loop. (b) Comparison of predictions for the baryon asymmetry versus chargino mass parameters μ and m₂. Left plot, using classical chiral force formalism (WKB) [20], assumes maximal CP violating phase ϕ and right plot using mass insertion in closed time path formalism, considers varying phase [21].

Figure 3.

Distribution of two Higgs doublet models passing experimental and consistency constraints, from ref. [41]. Horizontal axis is the predicted BAU in units of the observed value.

Figure 4.

Evolution of sample scalar potential V (h,s) with temperature, illustrating tree-level barrier.

Figure 5.

Scatter plot of dark matter density versus baryon asymmetry for the model with dark-matter induced EWBG. η is the pseudoscalar coupling of the DM to the scalar singlet, equation (4.1).

Figure 6.

(a) ATLAS upper limit on pair production cross section in the MSSM for lightest superpartner (dark matter) mass of 60 GeV from ref. [48]. Dash-dotted line is the predicted cross section. We can reinterpret as ϕ and the neutralino as χ to apply the constraints to our model. (b) Diagram for producing gamma ray lines from dark matter annihilation. (c) Diagram generating DM scattering on nuclei, in the presence of non-vanishing 〈s〉 VEV.

Figure 7.

Generation of dimension-5 contribution to top quark mass, , through a heavy vectorlike top partner.