General one-loop renormalization group evolutions and electroweak symmetry breaking in the (M+1)SSM

We study analytically the general features of electroweak symmetry breaking in the context of the Minimal Supersymmetric Standard Model extended by one Higgs singlet. The exact analytical forms of the renormalization group evolutions of the Yukawa couplings and of the soft supersymmetry breaking parameters are derived to one-loop order. They allow on one hand controllable approximations in closed analytical form, and on the other a precise study of the behaviour of infrared quasi fixed point regimes which we carry out. Some of these regimes are shown to be phenomenologically inconsistent, leading to too small an effective μ-parameter. The remaining ones serve as a suitable benchmark to understand analytically some salient aspects, often noticed numerically in the literature, in relation to the electroweak symmetry breaking in this model. The study does not need any specific assumption on tan β or on boundary conditions for the soft supersymmetry breaking parameters, thus allowing a general insight into the sensitivity of the low energy physics to high energy assumptions. Allocataire MNESR On leave of absence from Université Louis Pasteur, Strasbourg. 1