Open Access Published by De Gruyter Open Access

Volume 12 Issue 7

July 2014

Issue of Open Physics

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Contents
Journal Overview

Open Access June 21, 2014

Scalar particles mass spectrum and localization on FRW branes embedded in a 5D de Sitter bulk

Marina-Aura Dariescu, Ciprian Dariescu

Page range: 453-459

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Abstract

In this paper, we study the scalar fields evolving on a FRW brane embedded in a five-dimensional de Sitter bulk. The scale function and the warp factor, solutions of the Einstein equations, are employed in the five-dimensional Gordon equation describing the massive scalar field, whose wave function depends on the cosmic time and on the extra-dimension. We point out the existence of bounded states and find a minimum value of the effective four-dimensional mass. For the test (scalar) field envelope along the extra-dimension, we derive the corresponding Schrödinger-like equation which is formally that for the Pöschl-Teller potential. Accordingly, we have obtained the quantization law for the mass parameter of the tested scalar field.

Open Access June 21, 2014

Darwin curves and galaxy arms

Jin He

Page range: 460-465

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Abstract

In the natural world, there exists one kind of structure which is beyond the scope of human laboratorial experiment. It is the structure of galaxies which is usually composed of billions of stars. Spiral galaxies are flat disk-shaped. There are two types of spiral galaxies. The spiral galaxies with some bar-shaped pattern are called barred spirals, and the ones without the pattern are called ordinary spirals. Longer-wavelength galaxy images (infrared, for example) show that ordinary spiral galaxies are basically an axi-symmetric disk that is called exponential disk. For a planar distribution of matter, Jin He defined Darwin curves in the plane as such that the ratio of the matter densities at both sides of the curve is constant along the curve. Therefore, the arms of ordinary spiral galaxies are Darwin curves. Now an important question is that: Are the arms of barred spiral galaxies the Darwin curves too? Fortunately, Jin He designed a piece of Galaxy Anatomy graphic software. With the software, not only can people simulate the stellar density distribution of barred spiral galaxies but also can draw the Darwin curves of the simulated galaxy structure. This paper shows partial evidence that the arms of galaxy NGC 3275, 4548 and 5921 follow Darwin curves.

Open Access June 21, 2014

Analysis of the fluctuations of a laser beam due to thermal turbulence

Sphumelele Ndlovu, Naven Chetty

Page range: 466-472

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Abstract

A laser beam propagating in air and passing through a point diffraction interferometer (PDI) produces stable interferograms that can be used to extract wavefront data such as major atmospheric characteristics: turbulence strength, inner scale and outer scale of the refractive index. These parameters need to be taken into consideration when developing defense laser weapons since they can be affected by thermal fluctuations that are due to the changes in temperature in close proximity to the propagating beam and results in phase shifts that can be used to calculate the temperature which causes wavefront perturbations on a propagating beam.

Open Access June 21, 2014

One-dimensional Bose-Hubbard model with pure three-body interactions

Tomasz Sowiński

Page range: 473-479

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Abstract

The extended Bose-Hubbard model with pure three-body local interactions is studied using the Density Matrix Renormalization Group approach. The shapes of the first two insulating lobes are discussed, and the values of the critical tunneling for which the system undergoes the quantum phase transition from insulating to superfluid phase are predicted. It is shown that stability of insulating phases, in contrast to the standard Bose-Hubbard model, is enhanced for larger fillings. It is also shown that, on the tip of the boundary of the insulating phase, the model under consideration belongs to the Berenzinskii-Kosterlitz-Thouless universality class.

Open Access June 21, 2014

Travelling wave solutions: A new approach to the analysis of nonlinear physical phenomena

Khosro Sayevand, Dumitru Baleanu, Mojtaba Fardi

Page range: 480-489

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Abstract

In this manuscript, a reliable scheme based on a general functional transformation is applied to construct the exact travelling wave solution for nonlinear differential equations. Our methodology is investigated by means of the modified homotopy analysis method which contains two convergence-control parameters. The obtained results reveal that the proposed approach is a very effective. Several illustrative examples are investigated in detail.

Open Access June 21, 2014

Deformation effects on isospin mixing and isobar analogue resonance for 74−80Kr isotopes

Hasan Aygör, Serdar Ünlü, Neçla Çakmak, Cevat Selam

Page range: 490-498

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Abstract

Pyatov’s method has been applied to investigate Fermi beta transitions in deformed 74–80Kr isotopes. This self-consistent method, which was used to study the isobar analogue states in the spherical odd-odd nuclei, has to date not been applied for the isobar analogue states in deformed nuclei. The nucleon-nucleon residual interaction has been included so that the broken isospin symmetry in the mean field approximation has been restored and the strength parameter of the effective interaction has been taken out to be a free parameter. The energies and wave functions of the isobaric analogue excitations in 74–80Rb isotopes have been obtained within the framework of the pnQRPA method. The probability of the isospin mixing in the ground states and the centroid energies of the isobar analogue resonance have been presented and the deformation effects on these quantities have been quantified.

Open Access June 21, 2014

Eigenvalues and eigenfunctions of the anharmonic oscillator V(x, y) = x 2 y 2

Francisco Fernández, Javier Garcia

Page range: 499-502

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Abstract

We obtain sufficiently accurate eigenvalues and eigenfunctions for the anharmonic oscillator with potential V(x, y) = x 2 y 2 by means of three different methods. Our results strongly suggest that the spectrum of this oscillator is discrete in agreement with early rigorous mathematical proofs and against a recent statement that cast doubts about it

Open Access June 21, 2014

Analytical approximate solutions to the Thomas-Fermi equation

Vasile Marinca, Remus-Daniel Ene

Page range: 503-510

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Abstract

The purpose of this paper is to show how to use the Optimal Homotopy Asymptotic Method (OHAM) to solve the nonlinear differential Thomas-Fermi equation. Our procedure does not depend upon small parameters and provides us with a convenient way to optimally control the convergence of the approximate solutions. An excellent agreement was found between our approximate results and numerical solutions, which prove that OHAM is very efficient in practice, ensuring a very rapid convergence after only one iteration.

Open Access June 21, 2014

A new method of calculation in the Fractional Quantum Hall Effect regime

Zine Bentalha, Larabi Moumen, Tarik Ouahrani

Page range: 511-516

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Abstract

The electron-electron and electron-background interaction energies are calculated analytically for systems with up to N = 6 electrons. The method consists of describing the position vectors of electrons using complex coordinates and all the interaction energies with complex notation, whereby simplifications become possible. As is known, in this type of calculation, complicated expressions involving integrals over many variables are encountered and the trick of using complex coordinates greatly facilitates the exact calculation of various quantities. Contrary to previous analytical calculations, using complex coordinates avoids complicated trigonometric functions from appearing in the integrand, simplifying the exact evaluation of the integrals. The method we have used can be straightforwardly extended to larger systems with N > 6 electrons.

Open Access June 21, 2014

Two dimensional fractional projectile motion in a resisting medium

Juan Rosales, Manuel Guía, Francisco Gómez, Flor Aguilar, Juan Martínez

Page range: 517-520

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Abstract

In this paper we propose a fractional differential equation describing the behavior of a two dimensional projectile in a resisting medium. In order to maintain the dimensionality of the physical quantities in the system, an auxiliary parameter k was introduced in the derivative operator. This parameter has a dimension of inverse of seconds (sec)−1 and characterizes the existence of fractional time components in the given system. It will be shown that the trajectories of the projectile at different values of γ and different fixed values of velocity v 0 and angle θ, in the fractional approach, are always less than the classical one, unlike the results obtained in other studies. All the results obtained in the ordinary case may be obtained from the fractional case when γ = 1.

About this journal

Open Physics (PHYS) is a peer-reviewed, open access, electronic journal devoted to the publication of fundamental research results in all fields of physics. The journal provides the readers with free, instant, and permanent access to all content worldwide; and the authors with extensive promotion of published articles, long-time preservation, no space constraints and immediate publication.

Aims and Scope

The journal publishes research and review articles, rapid and short communications, comments and replies that cover the following areas of physical sciences:

Acoustics

Astrophysics,

Atomic and Molecular Physics,

Biological and Medical Physics,

Complex Networks, Socio- and Econophysics,

Computational Physics,

Condensed Matter Physics,

Cosmology and Gravitation,

Fluid Mechanics,

Geophysics,

Nanophysics,

Optics and Lasers,

Particle and Nuclear Physics,

Plasma Physics,

Statistical and Nonlinear Physics,

Surface Physics,

Theoretical and Mathematical Physics.