We carry out a detailed analysis of the general two Higgs doublet model with CP violation. We describe two different parametrizations of this model, and then study the Higgs boson masses and the trilinear Higgs couplings for these two parametrizations. Within a rather general model, we find that the trilinear Higgs couplings have a significant dependence on the details of the model, even when the lightest Higgs boson mass is taken to be a fixed parameter. We include radiative corrections in the one-loop effective potential approximation in our analysis of the Higgs boson masses and the Higgs trilinear couplings. The one-loop corrections to the trilinear couplings of the two Higgs doublet model also depend significantly on the details of the model, and can be rather large. We study quantitatively the trilinear Higgs couplings, and show that these couplings are typically several times larger than the corresponding Standard Model trilinear Higgs coupling in some regions of the parameter space. We also briefly discuss the decoupling limit of the two Higgs doublet model.

We present an R-parity conserving model of sneutrino dark matter within a Higgsphilic Uð1Þ 0 extension of the minimal supersymmetric standard model. In this theory, the parameter and light Dirac neutrino masses are generated naturally upon the breaking of the Uð1Þ 0 gauge symmetry. One of the right-handed sneutrinos is the lightest supersymmetric particle. The leptonic and hadronic decays of another sneutrino, taken to be the next-to-lightest superpartner, allow for a natural fit to the recent results reported by the PAMELA experiment. We perform a detailed calculation of the dark matter relic density in this scenario, and show that the model is consistent with the ATIC and Fermi LAT experiments.

We study a softly-broken supersymmetric model whose gauge symmetry is that of the standard model (SM) gauge group times an extra Abelian symmetry U (1) ′ . We call this gauge-extended model U (1) ′ model, and we study a U (1) ′ model with a secluded sector such that neutrinos acquire

We study the Higgs sector of the U(1) ′ -extended MSSM with CP violation. This is an extension of the MSSM Higgs sector by one singlet field, introduced to generate the µ term dynamically. We are particularly interested in non-standard decays of Higgs particles, especially of the lightest one, in the presence of CP violating phases for µ ef f and the soft parameters. We present analytical expressions for neutral and charged Higgs bosons masses at tree and one-loop levels, including contributions from top and bottom scalar quark sectors. We then study the production and decay channels of the neutral Higgs for a set of benchmark points consistent with low energy data and relic density constraints. Numerical simulations show that a Higgs boson lighter than 2m W can decay in a quite distinctive manner, including invisible modes into two neutralinos (h →χ 0χ0 ) up to ∼ 50% of the time, when kinematically allowed. The branching ratio into h →bb, the dominant decay in the SM, is reduced in some U (1) ′ models and enhanced in others, while the branching ratios for the decays h → τ + τ − , h → W W * and h → ZZ * → 4ℓ are always reduced with respect to their SM expectations. This possibility has important implications for testing the U (1) ′ model both at the LHC and later at the ILC.