SUSY Variants of the Electroweak Phase Transition

TL;DR

The paper investigates whether SUSY extensions of the SM can yield a strongly first-order electroweak phase transition suitable for electroweak baryogenesis. It combines dimensional reduction to a three-dimensional effective theory, perturbative analyses, lattice comparisons, and a semi-analytic nonperturbative approach to assess the transition. It finds that while the SM fails to produce the required washout suppression for realistic Higgs masses, the MSSM with a light stop_R and the NMSSM with a sizable singlet can achieve $v_c/T_c \gtrsim 1$ for Higgs masses near 100 GeV, offering viable baryogenesis possibilities. The work highlights the need to understand bubble-wall dynamics and CP-violating sources and demonstrates the value of integrating perturbative, lattice, and nonperturbative methods to make robust predictions.

Abstract

The MSSM with a light right-handed stop and supersymmetric models with a singlet whose vev is comparable to that of the SU(2)_W Higgs allow for a strongly first-order electroweak phase transition even for a mass of the lightest Higgs around 100 GeV. After a short review of the standard model situation we discuss these supersymmetric models. We also compare perturbative calculations based on the dimensionally reduced 3-dimensional action with lattice results and present an analytic procedure based on an analogue of the stochastic vacuum model of QCD to estimate the nonperturbative contributions.

Figures (10)

• Figure 1:
• Figure 2: (from ref. [15]). The perturbatively calculated interface tension $\sigma$ (including $Z$-factor effect and gauge variations) vs. $x$ compared to lattice data from ref. [10] (squares), ref. [16] (triangles) and ref. [17] (circles).
• Figure 3: 1-loop graph contributing to the potential $V(\varphi^2,<g_3^2F^2>)$.
• Figure 4: Sketch of the potential $V(\varphi^2,<g_3^2F^2>)$ in $F^2$-direction for two different values of $\varphi^2$.
• Figure 5: (from ref. [13]). $m_{\rm conf}^2(p^2,m^2)$ and $\tilde{S}_F(p^2,m^2)$ in units of $(g_3^2)^2$ plotted a) for $m^2=0$ and b) $p^2=0$.