Stop-catalyzed baryogenesis beyond the MSSM

Nonminimal supersymmetric models that predict a tree-level Higgs mass above the minimal supersymmetric standard model (MSSM) bound are well motivated by naturalness considerations. Indirect constraints on the stop sector parameters of such models are significantly relaxed compared to the MSSM; in particular, both stops can have weak-scale masses. We revisit the stop-catalyzed electroweak baryogenesis (EWB) scenario in this context. We find that the LHC measurements of the Higgs boson production and decay rates already rule out the possibility of stop-catalyzed EWB. We also introduce a gauge-invariant analysis framework that may generalize to other scenarios in which interactions outside the gauge sector drive the electroweak phase transition.

Figure 1

Regions of stop parameter space allowed by the LHC Higgs measurements (blue—67% CL and green—95% CL) vs. the domain where the stop-catalyzed EWB can potentially be viable ($\xi >0$) in pink. Mass of the light stop is fixed at 100 GeV. The unphysical region (no solution for ${\theta }_t$) is shaded in purple.

Figure 2

Constraints and regions with a 1st-order EWPT in the ($m_{{\tilde{t}}_2},{\theta }_t$) plane, for the light stop mass $m_{{\tilde{t}}_1}=100\mathrm{GeV}$. The region allowed by Higgs fits at 95% CL is shaded in blue. The blue line shows the contour of $\xi =0$ and the red line shows the contour of $\xi =0.5$. The region between the black contours is allowed at the 95% CL if a nonzero Higgs invisible width is included (${\epsilon }_{\text{inv}}=0.1$ using the definitions of [61]).

Figure 3

Same as Fig. 2, zooming in on the regions where the light stop is mostly ${\tilde{t}}_L$ and ${\tilde{t}}_R$.