CTP Seminar
The talk has three disciplines: In the first part, we present an inflation model based on modifying the standard hybrid inflation model. The model connects a successful hybrid inflation scenario to the standard model Higgs sector via the electroweak vacuum stability. The proposed model results in an effective inflation potential of a hilltop type, with both the trans-Planckian and sub-Planckian inflation regimes consistent with the recent Planck/BICEP combined results. Reheating via the inflation sector decays to right-handed neutrinos is considered. We show that the couplings of the SM Higgs field to the inflation sector can guarantee the electroweak vacuum stability up to the Planck scale. In the second part, we adopt a standard FRW cosmology with a unified scenario, where the usual dark matter and dark energy sectors are replaced by a perfect or dissipative single unified dark fluid. The equation of state of such fluid can asymptote between two power laws. As a result, it enables fluid to have a smooth transition from dust at early times to dark energy at late times. The models are tested through different observational datasets. In the third part, we present a study about the thermodynamics of dyonic Taub-NUT-AdS solutions. We investigate in detail the possible phase structures of their solutions and analyze these phase structures by considering both the canonical and mixed ensembles.