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Kh. Saaidi

Publications and source records attributed to Kh. Saaidi.

46 records · Page 3Linked to original sources
arXiv2010

Spherical Symmetric Solution in f(R) Model Around Charged Black Hole

A static, asymptotically flat, spherically symmetric solutions is investigated in f(R) theories of gravity for a charged black hole. We have studied the weak field limit of f(R) gravity for the some f(R) model such as f(R) = R + epsilon h(R). In particular, weconsider the case lim_{R =0} {h(R)/ dh(R)/dR}=0 and find the space time metric for f(R) = R + {mu}^{4} /R and f(R) = R^{1-epsilon} theories of gravity far away a charged mass point.

gr-qc↗
arXiv2010

Group velocity control in a four level system through interacting dark resonances

We investigate dispersion and absorption properties of a weak probe field in a four level atomic system through interacting dark resonances. We show that two narrow peaks appears in the optical spectra due to the presence of interacting dark resonances. This two narrow peaks leads to the superluminal light propagation with strong absorption. However, if a weak incoherent pump field is exerted to the probe transition, then the peaks structures can be changed such that two absorption peaks transformed to two gain deeps. We Show that both subluminal and superluminal light propagation occur in this system, where controlled by the incoherent pumping strength.

quant-ph↗
arXiv2009

Standard Cosmological Evolution in f(R) Model to Kaluza Klein Cosmology

In this paper, using $f(R)$ theory of gravity we explicitly calculate cosmological evolution in the presence of a perfect fluid source in four and five dimensional, space time in which this cosmological evolution in self-creation is presented by Reddy et al 2009 Int. J. Theor. Phys. 48 10. An exact cosmological model is presented using a relation between Einstein gravity field equation components due to a metric with the same component from $f(R)$ theory of gravity. Some physics and kinematical properties of the model are also discussed.

gr-qc↗
arXiv2002

Inhomogenous Poisson Networks and Random Cellular Structures

we study the statistical properties of inhomogenous Poisson networks. we perform a detailed analysis of the statistical properties of Poisson networks and show that the topological properties of random cellular structures, can be derived from these models of random networks. we study both two and three dimensional networks with non uniform density and show that with a class of symmetric distribution $P(λ_{1}, λ_{2}, ..., λ_{N})$ Lewis and Aboav-Weaire laws are obeyed in these networks.

cond-mat.stat-mech↗
arXiv2002

More on Phase Structure of Nonlocal 2D Generalized Yang-Mills Theories (nlgYM$_2$'s)

We study the phase structure of nonlocal two dimensional generalized Yang - Mills theories (nlgYM$_2$) and it is shown that all order of $ϕ^{2k}$ model of these theories has phase transition only on compact manifold with $g = 0$(on sphere), and the order of phase transition is 3. Also it is shown that the $ϕ^2 + \frac{2α}{3}ϕ^3$ model of nlgYM$_2$ has third order phase transition on any compact manifold with $1 < g < 1+ \frac{\hat{A}}{|η_c|}$, and has no phase transition on sphere.

hep-th↗
arXiv2002

Effective Action for Self-Interacting Scalar Field in 3-dimensional Ball

In this paper we have considered the renormalized one-loop effective action for massless self-interacting scalar field in the 3-dimensional ball. The scalar field satisfies Dirichlet boundary condition on the ball. Using heat kernel expansion method we calculate the divergent part of effective action, then by bag model renormalization procedure we obtain the renormalized one-loop effective action.

hep-th↗
arXiv2000

Generating Functional and Large N-Limit of Nonlocal 2D Generalized Yang-Mills Theories ($nlgYM_2$'s)

Using the path integral method, we calculate the partition function and generating functional (of the field strengths) on the nonlocal generalized 2D Yang - Mills theories ($nlgYM_2$'s), which is nonlocal in auxiliary field [14]. Our calculations is done for general surfaces. We find a general expression for free energy of $W(ϕ) = ϕ^{2k}$ in $nlgYM_2$ theories at the strong coupling phase (SCP) regime ($A > A_c$) for large groups. In the specific $ϕ^4$ model, we show that the theory has a third order phase transition.

hep-th↗
arXiv2000

More on generalized simplicial chiral models

By generalizing the auxiliary field term in the Lagrangian of simplicial chiral models on a (d-1)-dimensional simplex, the generalized simplicial chiral models has been introduced in \c{Ali}. These models can be solved analytically only in d=0 and d=2 cases at large-N limit. In d=0 case, we calculate the eigenvalue density function in strong regime and show that the partition function computed from this density function is consistent with one calculated by path integration directly. In d=2 case, it is shown that all $V= {\rm Tr}(AA^{\d})^n$ models have a third order phase transition, same as the 2-dimensional Yang-Mills theory.

hep-th↗
arXiv1996

Analysis of Poisson Networks and Their Relation with Random Cellular Structures

We perform a detailed analysis of the statistical properties of Poisson networks and show that the metric and topological properties of random cellular structures, can not be derived from simple models of random networks based on a poisson point distribution [1]. In particular we show that Lewis and Aboav-Wieare laws are not obeyed in these network.

cond-mat↗