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Khaled Saaidi

Publications and source records attributed to Khaled Saaidi.

30 records · Page 2Linked to original sources
arXiv2012

Stability of Ghost Dark Energy in CBD Model of Gravity

We study the stability of the ghost dark energy model versus perturbation. Since this kind of dark energy is instable in Einsteinian general relativity theory, then we study a new type of Brans-Dicke theory which has non-minimal coupling with matter which is called chameleon Brans-Dicke (CBD) model of gravity. Due to this coupling the equation of conservation energy is modified. For considering the stability of the model we use the adiabatic squared sound speed, $c_s^2$, whose sign of it determines the stability of the model in which for $c_s^2 >0 $ the model is stable and for $c_s^2 <0 $ the model is instable. However, we study the interacting and non-interacting version of chameleon Brans-Dicke ghost dark energy (CBDGDE) with cold dark matter in non flat FLRW metric. We show that in all cases of investigation the model is stable with a suitable choice of parameters.

gr-qc↗
arXiv2011

$γ$ Parameter and Solar System constraint in Chameleon Brans Dick Theory

The post Newtonian parameter is considered in the Chameleon-Brans-Dicke frame. In the first step, the general form of this parameter and also effective gravitational constant is obtained. An arbitrary function for $f(Φ)$, which indicates the coupling between matter and scalar field, is introduced to investigate validity of solar system constraint. It is shown that Chameleon-Brans-Dicke model can satisfy the solar system constraint and gives us an $ω$ parameter of order $10^4$, which is in comparable to the constraint which has been indicated in {\cite{17-a}}.

gr-qc↗
arXiv2010

Absorption-free superluminal light propagation in a V-type system

Dispersion and absorption properties of a weak probe field in a three-level V-type atomic system is studied. By application of indirect incoherent pump fields the effect of populating upper levels on optical properties of the atomic medium in presence of a strong coherent pump field is investigated. It is shown that the slope of dispersion changes from positive to negative just by changing the intensity of the coherent or indirect incoherent pump fields. It is demonstrated that the absorption-free subluminal and superluminal light propagation appears in this system.

quant-ph↗
arXiv2005

Non-local 2D Generalized Yang-Mills theories on arbitrary surfaces with boundary

The non-local generalized two dimensional Yang Mills theories on an arbitrary orientable and non-orientable surfaces with boundaries is studied. We obtain the effective action of these theories for the case which the gauge group is near the identity, $U\simeq I$. Furthermore, by obtaining the effective action at the large-N limit, it is shown that the phase structure of these theories is the same as that obtain for these theories on orientable and non-orientable surface without boundaries. It is seen that the $ϕ^2$ model of these theories on an arbitrary orientable and non-orientable surfaces with boundaries have third order phase transition only on $g=0$ and $r=1$ surfaces, with modified area $\tilde{A}+{\cal A}/2$ for orientable and $\bar{A}+\mathcal{A}$ for non-orientable surfaces respectivly.

hep-th↗
arXiv2005

Wath Time an Incident Wave Packet is Reflected?

We study the one dimensional time dependent Schrödinger equation for a potential step with $E < V_0$. We obtain the wave is not instantaneously reflected, but for a few moment of time the wave packet penetrate into inaccessible classically region and then reflected. So it is shown that one can write the peneterated wave paket as superposition of incident and reflected wave packets like.

quant-ph↗
arXiv2003

More on Exact $\CP$-Symmetric Quantum Mechanics

In this article, we discussed certain properties of non-Hermitian $\CP$-symmetry Hamiltonian, and it is shown that a consistent physical theory of quantum mechanics can be built on a ${\cal C} \CP$-symmetry Hamiltonian. In particular, we show that these theories have unitary time evolution, and conservation probability. Furthermore, transition from quantum mechanics to classical mechanics is investigate and it is found that the Ehrenfest theorem is satisfied.

quant-ph↗
arXiv2003

A Dirac Particle in a Complex Potential

It has been observed that a quantum mechanical theory need not to be Hermitian to have a real spectrum. In this paper we obtain the eigenvalues of a Dirac charged particle in a complex static and spherically symmetric potential. Furthermore, we study the Complex Morse and complex Coulomb potentials.

quant-ph↗
arXiv2003

Eigenvalue Spectrum of a Dirac Particle in Static and Spherical Complex Potential

It has been observed that a quantum theory need not to be Hermitian to have a real spectrum. We study the non-Hermitian relativistic quantum theories for many complex potentials, and we obtain the real relativistic energy eigenvalues and corresponding eigenfunctions of a Dirac charged particle in complex static and spherically symmetric potentials. Complex Dirac-Eckart, complex Dirac-Rosen-Morse II, complex Dirac-Scarf and complex Dirac-Poschl-Teller potential are investigated.

quant-ph↗
arXiv2003

Large-N limit of the non-local 2D Yang-Mills and generalized Yang-Mills theories on a cylinder

The large-group behavior of the nonlocal YM$_2$'s and gYM$_2$'s on a cylinder or a disk is investigated. It is shown that this behavior is similar to that of the corresponding local theory, but with the area of the cylinder replaced by an effective area depending on the dominant representation. The critical areas for nonlocal YM$_2$'s on a cylinder with some special bounary conditions are also obtained.

hep-th↗
arXiv2003

Large-N limit of non-local 2D generalized Yang-Mills theories on non-orientable surface

The large-group behavior of the non-local two dimensional generalized Yang-Mills theories (nlgYM$_2$'s) on arbitrary closed non-orientable surfaces is investigated. It is shown that all order of $ϕ^{2k}$ model of these theories have thired order phase transition only on projective plane (RP$^2$). Also the phase structure of $ϕ^2 + \fracγ{4}ϕ^4$ model of nlgYM$_2$ is studied and it is found that for $γ>0$, this model has third order phase transition only on RP$^2$ and for $γ<0$ it has third order phase transition on any closed non-orientable surfaces except RP$^2$ and Klein bottel.

hep-th↗
arXiv2000

Nonlocal two-dimensional Yang-Mills- and generalized Yang-Mills-theories

A generalization of the two-dimensional Yang-Mills and generalized Yang-Mills theory is introduced in which the building B-F theory is nonlocal in the auxiliary field. The classical and quantum properties of this nonlocal generalization are investigated and it is shown that for large gauge groups, there exist a simple correspondence between the properties a nonlocal theory and its corresponding local theory.

hep-th↗