On the smallness of the cosmological constant in SUGRA models

In no--scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. We consider the breakdown of these symmetries and present a minimal SUGRA model motivated by the multiple point principle, in which the total vacuum energy density is naturally tiny. In order to reproduce the observed value of the cosmological constant and preserve gauge coupling unification, an additional pair of $5+\bar{5}$--plets of superfields has to be included in the particle content of the considered model. These extra fields have masses of the order of the supersymmetry breaking scale; so they can be detected at future colliders. We also discuss the supersymmetry breakdown and possible solution of the cosmological constant problem by MPP in models with an enlarged gauge symmetry.Comment: 28 pages, 3 figures, some minor changes to the text, references adde

On the Smallness of the Cosmological Constant in SUGRA Models Inspired by Degenerate Vacua

In the no-scale supergravity global symmetries protect local supersymmetry and a zero value for the cosmological constant. The breakdown of these symmetries, which ensures the vanishing of the vacuum energy density, results in a set of degenerate vacua with broken and unbroken supersymmetry leading to the natural realisation of the multiple point principle (MPP). In the MPP inspired SUGRA models the cosmological constant is naturally tiny.Comment: Parallel talk at SUSY09, Boston, USA, June 2009, 5 page

Multiple point principle as a mechanism for the suppression of FCNC and CP--violation phenomena in the 2HDM

We argue that multiple point principle (MPP) can be used to ensure CP conservation and the absence of flavour changing neutral currents within the two Higgs doublet model (2HDM). We also discuss Higgs phenomenology in the MPP inspired 2HDM.Comment: Submitted for the SUSY07 proceedings, 4 pages, LaTeX, 2 eps figures,CERN preprint number added, references update

Particle spectrum in modified NMSSM

The restrictions on the lightest Higgs boson mass in the minimal supersymmetric models are briefly reviewed. The particle spectrum is considered in the framework of the simplest modification of NMSSM that allows to avoid the domain wall problem and to get the self--consistent solution in the strong Yukawa coupling limit. The lightest Higgs boson mass in the investigated model can reach $125 GeV$ at values of $\tan\beta\ge 1.9$ and does not exceed $130.5\pm 3.5 GeV$.Comment: 4 pages, LaTeX2e. Talk given at the SUSY 2001 Conference in JINR, Dubna, Russi