A. Tofighi

The intrinsic damping of the fractional oscillator

We obtain analytical expressions for the time rate of change of the potential energy, the kinetic energy and the total energy of a fractional oscillator in terms of the products of Mittag–Leffler functions. We propose a definition for the intrinsic damping force of this oscillator. We obtain a general expression for this damping force. An expression for this damping force in the asymptotic limit (ωt→0) is also obtained.

Stabilization of modulus in Randall-Sundrum model I by bulk scalar fields

We consider the case of self-interacting scalar field for the stabilization of modulus in the Randall–Sundrum model I. This scalar field is non-minimally coupled to the Ricci curvature scalar. We find the compactification radius and we discuss the implications of our results for the cases of massive and massless scalars.

An Especial Fractional Oscillator

We propose a peculiar fractional oscillator. By assuming that the motion takes place in a complex media where the level of fractionality is low, we find that the time rate of change of the energy of this system has an oscillatory behavior.

Strong Electroweak Phase Transition in a Model with Extended Scalar Sector

We consider an extension of the Standard Model (SM) with additional gauge singlets which exhibits a strong first-order phase transition. Due to this first-order phase transition in the early universe gravitational waves are produced. We estimate the contributions such as the sound wave, the bubble wall collision, and the plasma turbulence to the stochastic gravitational wave background, and we find that the strength at the peak frequency is large enough to be detected at future gravitational interferometers such as eLISA. Deviations in the various Higgs boson self-couplings are also evaluated.

Extended Higgs sector of supersymmetric models

The Higgs sector of the MSSM may be extended to solve the μ problem by the addition of a gauge singlet scalar field. We consider two singlet extended Higgs models. For the first model, we prove that in the absence of soft supersymmetry (SUSY) breaking terms a true SUSY breaking minimum does not exist. For the second model, we show that an electroweak symmetry breaking transition from a broken SUSY phase to our current universe is allowed.

The scalar sector of split-fermion models

In the split-fermion model, fermions are localized by scalars. We discuss single-scalar, two-scalar and three-scalar models. In all of these models, we find the localizer. We also calculate the Higgs profile.

Mass of the Stabilized Radion in the Limit of Finite Quartic Coupling

We present an exact treatment of the modulus stabilization condition with the general boundary conditions of the bulk scalar field in the Randall-Sundrum model. We find analytical expressions for the value of the modulus and the mass of the radion.

Vacuum Expectation Value Profiles of the Bulk Scalar Field in the Generalized Randall-Sundrum Model

In the generalized Randall-Sundrum warped brane-world model the cosmological constant induced on the visible brane can be positive or negative. In this paper we investigate profiles of vacuum expectation value of the bulk scalar field under general Dirichlet and Neumann boundary conditions in the generalized warped brane-world model. We show that the VEV profiles generally depend on the value of the brane cosmological constant. We find that the VEV profiles of the bulk scalar field for a visible brane with negative cosmological constant and positive tension are quite distinct from those of Randall-Sundrum model. In addition we show that the VEV profiles for a visible brane with large positive cosmological constant are also different from those of the Randall-Sundrum model. We also verify that Goldberger and Wise mechanism can work under nonzero Dirichlet boundary conditions in the generalized Randall-Sundrum model.

Temperature effects on the fermion localization in smooth space generated by a bounce

In this paper, we investigate the effects of temperature in the braneworld model, made of a scalar with bounce-type configurations which can be coupled to gravity minimally or nonminimally. It is shown that the smooth warp factor of the model delocalizes at the critical temperature. We also study temperature effects on the localization of fermions on the thermal bouncing brane with gravity.

Domain Wall Splitting in Extra Dimension

We study the splitting of domain walls in 5-dimensional flat Minkowski spacetime. To construct a domain wall structure we utilize a potential of the form and for simplicity we assume the scalar field to be real. We also assume the coefficient a to be temperature-dependent. We find exact analytical expressions for the energy density of the domain wall and from this expression we find close analytical form for the separation of the divided domain walls. We find that near critical temperature the domain walls split. At the critical temperature, the domain walls rejoin. In the region above this critical temperature, the kink solution is nontopological. We find that the phenomena of splitting of domain walls occurs in this region as well. This effect is especially manifest near the inflection point of the potential.