Strong electroweak phase transitions without collider traces

Abstract

We discuss the question if the upcoming generation of collider and low-energy experiments can successfully probe the nature of the electroweak phase transition. In particular, we are interested in phase transitions strong enough for electroweak baryogenesis or even for a production of gravitational radiation observable by the Big Bang Observer. As an explicit example, we present an analysis in a singlet extension of the Standard Model. We focus on the region in parameter space where the model develops no significant deviation in its low energy phenomenology from the Standard Model. Nevertheless, this class of models can develop a very strong phase transition.

Figures (6)

• Figure 1: The additional Feynman rules involving the singlets under the assumption of vanishing Higgs-singlet mixing, $\bar{\mu}^2_{hs} = 0$.
• Figure 2: One-loop diagrams that contribute to decay and mixing of the singlet with the Higgs.
• Figure 3: Dominant contributions to singlet annihilation.
• Figure 4: An example of the paths of the extrema as functions $x(v)$ in scalar field space and the corresponding values of the potential. The two circles denote the local minima in the potential. For small Higgs VEV $v$, the potential has two minima and one maximum with respect to $x$. For large $v$ only one minimum remains. The fields have to cross the ridge to tunnel from the symmetric to the broken phase. In addition, the plot shows a typical path we choose to determine the tunneling action.
• Figure 5: The tunnel action $S_3/T$ as a function of the temperature for different values of $\bar{\mu}_s$. The circles denote the temperature at the end of the phase transition determined with the methods from ref. Huber:2007vva.