Three types of thick branes, i.e., Poincaré, de Sitter and Anti-de Sitter brane are considered. They are realized as the non-singular solutions of the Einstein equations with the non-trivial dilatons and the potentials. The scalar perturbations of these systems are also investigated. We find that the effective potentials of the master equations of the scalar perturbations are positive definite ...

We review the status of a quasi degenerate doublets in nuclei, called pseudospin doublets, which were discovered about thirty years ago and the origins of which have remained a mystery, until recently. We show that pseudospin doublets originate from an SU(2) symmetry of the Dirac Hamiltonian which occurs when the scalar and vector potentials are opposite in sign but equal in magnitude. Furtherm...

Braneworld scenarios with compact extra dimensions need the volume of the extra space to be stabilized. Goldberger and Wise have introduced a simple mechanism, based on the presence of a bulk scalar field, able to stabilize the radius of the Randall-Sundrum model. Here, we transpose the same mechanism to generic single-brane and two-brane models, with one extra dimension and arbitrary scalar po...

We examine innationary universe models driven by scalar elds with logarithmic potentials of the form V () = V 0 p (ln) q. Combining the slow-roll approximation with asymptotic techniques, we identify regions of the potential where innation may occur and obtain analytic expressions for the evolution of the eld and the metric in these cases. We construct a family of exact solutions to the equatio...

We review the status of quasi-degenerate doublets in nuclei, called pseudospin doublets, which were discovered about thirty years ago and the origins of which have remained a mystery, until recently. We show that pseudospin doublets originate from an SU(2) symmetry of the Dirac Hamiltonian which occurs when the sum of the scalar and vector potentials is a constant. Furthermore, we survey the ev...

Scalar (density) and tensor (gravity-wave) perturbations provide the basis for the fundamental observable consequences of inflation, including CBR anisotropy and the fluctuations that seed structure formation. In general, these perturbations are nearly scale invariant (Harrison-Zel’dovich spectrum), though slight deviation from scale invariance (“tilt”) can have significant consequences for bot...

In this paper, the model of the holographic Chaplygin gas has been extended to two general cases: first the case of a modified variable Chaplygin gas and second the case of the viscous generalized Chaplygin gas. The dynamics of the model is expressed by the use of scalar fields and scalar potentials.

In this manuscript, we present a generalization of the interacting holographic dark energy model using two equations of states for the dark energy: the modified variable Chaplygin gas and the viscous generalized Chaplygin gas. The dynamics of the model are expressed by the use of scalar fields and the scalar potentials. PACS numbers: 98.80.Cq, 98.80.-k, 98.80.Jk ∗[email protected]

We obtain Q-ball solutions in noncommutative scalar field theory with a global U(1) invariance. The Q-ball solutions are shown to be classically and quantum mechanically stable. We also find that “excited Q-ball” states exist for some class of scalar potentials, which are classically stable in the large noncommutativity limit.

We study the late time evolution of flat and negatively curved FRW models with a perfect fluid matter source and a scalar field having an arbitrary non-negative potential function V (φ). We prove using a dynamical systems approach four general results for a large class of non-negative potentials which show that almost always the universe ever expands. In particular, for potentials having a loca...