Electroweak phase transition beyond the SM

In the framework of the two-Higgs-doublet model with temperature-dependent effective parameters λ 1,...7 (T ) we define the four bifurcation sets which appear as a consequence of the condition det∂ 2 U i j /∂ v i ∂ v j =0 for the stability matrix.Numerical investigations of the electroweak phase transition are performed for the full MSSM parameter space (m H ± , tgβ , A t,b , µ, m Q , m U , m D ) using the temperature-dependent effective parameters λ 1 -λ 5 (T ) calculated at the one-loop in the imaginary time formalism.Four types of transitions can take place in the MSSM background field space (v 1 , v 2 ).They are different in the direction, defined by a critical angle in the (v 1 , v 2 ) plane, and in the strength, which is estimated by means of Shaposhnikov criteria v c /T c >1. Extensive regions in the (A t,b , µ) plane correspond to the strongly first order phase transition.The case of light top quark superpartner is favored, giving an acceptable configurations of surfaces for extrema of the effective potential.

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