The cross sections for the lightest neutral Higgs pair production at the one-loop level in photon-photon collisions are calculated in the Minimal Supersymmetric Standard Model(MSSM). We find that the contributions to the lightest Higgs boson pair production cross sections arising from the genuine supersymmetric virtual particles dominate over that arising from the virtual particles in the two-H...

A study of Rb and Rc is presented in the context of a Two Higgs Doublet Model (2HDM) with flavor changing scalar currents (FCSC). Implications of the model for the ρ-parameter and for b → sγ are also considered. The experimental data on Rb places stringent constraints on the model parameters. The configuration of the model needed to account for Rb is found to be irreconcilable with constraints ...

CP violating effects in top quark pair production at the future 2 TeV pp̄ Tevatron and 14 TeV pp LHC colliders are investigated. We study three kinds of CP violating sources: the supersymmetric CP-odd phase of the stop trilinear soft breaking term: arg(At), the CP-odd parameter in two-Higgs doublet extensions of the standard model(2HDM), and the model-independent top quark chromoelectric dipole ...

The most general Two Higgs Doublet Model (2HDM) allows both for the explicit and the spontaneous CP violation in the scalar sector. Here we discuss CP violation in terms of basisindependent quantities and show how using two different sets of known CP-odd weak-basis invariants one can distinguish between CP conservation, explicit CP violation and spontaneous CP violation. The special case of CP ...

The Higgs potential of the two-Higgs-doublet model can have several minima with different properties. We discuss a possibility that a heavy fermion, if trapped in a microscopic false vacuum bubble, might become light enough to prevent the bubble from the collapse. The Standard Model relies on the Higgs mechanism of the electroweak symmetry breaking, whose details are yet not known. Its simplest...

We consider an extension of the Standard Model by heavy right-handed neutrinos and heavy Higgs doublets and show, using a renormalization group approach, that this model can simultaneously provide an explanation for the small neutrino masses and for the mild hierarchy observed between the atmospheric and the solar mass splittings, even when the extra degrees of freedom are very heavy. We analys...