Physics - General Physics Publications (50)

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Physics - General Physics Publications

Formation of molecular H2 and O2 is experimentally studied under laser exposure of water colloidal solution to radiation of a Nd:YAG laser at pulse duration of 10 ns and laser fluence in the liquid of order of 100 J/cm2. It is found the partial pressure of both H2 and O2 first increases with laser exposure time and saturates at exposures of order of 1 hour. The balance between O2 and H2 content depends on the laser energy fluence in the solution and is shifted towards H2 at high fluences. Read More


In this paper I show that the Einstein-Podolsky-Rosen-Bohm Gedankenexperiment and so-called entanglement of photons have a simple explanation within the framework of classical electrodynamics if we take into account the discrete (atomic) structure of the detectors and a specific nature of the light-atom interaction. In this case we do not find such a paradox as "spooky action at a distance". I show that CHSH criterion in EPRB Gedankenexperiment with classical light waves can exceed not only a maximum value S_HV=2 which is predicted by the local hidden-variable theories but also the maximum value S_QM=2. Read More


I show that a very simple model in the context of Newtonian physics promoted to a first approximation of general relativity can mimic Dark matter and explain most of its intriguing properties. Namely: i) Dark matter is a halo associated to ordinary matter; ii) Dark matter does not interact with ordinary matter nor with itself; iii) Its influence grows with the size of the aggregate of ordinary matter that is considered, and iv) Dark matter influences the propagation of light. Read More


The problem of the search for the satellites of the exoplanets (exomoons) is discussed recently. There are very many satellites in our Solar System. But in contrary of our Solar system, exoplanets have significant eccentricity. Read More


This paper critically considers the main interpretations of the wave function and offers an interpretation in which wave function is a consequence of subquantum processes taking place at the level of the organization of matter which underlies the phenomena described by quantum mechanics, i.e. in the physical vacuum. Read More


In the Majorana equation for particles with arbitrary spin, wave packets occur due to not only the uncertainty that affects position and momentum but also due to infinite components with decreasing mass that form the Majorana spinor. In this paper, we prove that such components contribute to increase the spreading of wave packets. Moreover, Zitterbewegung takes place in both the time propagation of Dirac wave packets and in Majorana wave packets. Read More


Starting from a statistical model of the electron, which explains spin and spin measurements in terms of a probability density distribution resulting from a rapidly changing angular momentum during an extended Zitterbewegung, a light-like model of electron and Fermions is formulated. This model describes individual particles in terms of paths of a moving quantum. It is shown that this description allows one to reproduce observable properties as path-averages over a period of the fast extended Zitterbewegung in elementary calculations. Read More


Approximate bound state solutions of the spinless Salpeter equation for the Hellmann potential are studied for heavy particles. By using functional analysis method, an analytical expression for the energy levels, and the corresponding eigenfunctions of the system are obtained in terms of the hypergeometric functions. The analytical results for the Yukawa and Coulomb potentials are also studied as special cases. Read More


The algebra of the generators for infinitesimal transformations of the $\Gamma={1 \over 2}$ representation of causal spinor fields (Dirac fields) \emph{explicitly} constructs the Minkowski metric \emph{within} the internal group space as a consequence of non-vanishing commutation relations between generators that carry a single space-time index. This representation is a subgroup of the set of all of the generators that transform under the group GL(4). The sixteen hermitian generators of GL(4) include the three angular momentum spin matrices, a matrix proportional to the Dirac matrix $\gamma^0$, and 12 additional matrices that have the same number of degrees of freedom as SU(3)$\times$SU(2)$\times$U(1). Read More


Considering a spherically-symmetric non-static cosmological flat model of Robertson-Walker universe we have investigated the problem of perfect fluid distribution interacting with the gravitational field in presence of massive scalar field and electromagnetic field in B-D theory. Exact solutions have been obtained by using a general approach of solving the partial differential equations and it has been observed that the electromagnetic field cannot survive for the cosmological flat model due to the influence caused by the presence of massive scalar field. Read More


The problem of cylindrically symmetric vacuum solutions of Brans-Dicke scalar fields has been studied. Exact solutions have been obtained for the vacuum B-D field equations for the cylindrically symmetric Einstein-Rosen metric. The solutions obtained in the present work are generalized solutions of the problem which has been studied by Rao et al. Read More


According to a traditional point of view Boltzmann entropy is intimately related to linear Fokker-Planck equations (Smoluchowski, Klein-Kramers, and Rayleigh equations) that describe a well-known nonequilibrium phenomenon: (normal) Brownian motion of a particle immersed in a thermal bath. Nevertheless, current researches have claimed that non-Boltzmann entropies (Tsallis and Renyi entropies, for instance) may give rise to anomalous Brownian motion through nonlinear Fokker-Planck equations. The novelty of the present article is to show that anomalous diffusion could be investigated within the framework of non-Markovian linear Fokker-Planck equations. Read More


This article is the second in a series of two presenting the Scale Relativistic approach to non-differentiability in mechanics and its relation to quantum mechanics. Here, we show Schroedinger's equation to be a reformulation of Newton's fundamental relation of dynamics as generalized to non-differentiable geometries in the first paper \cite{paper1}. It motivates an alternative interpretation of the other axioms of standard quantum mechanics in a coherent picture. Read More


We have obtained the Vlasov equation and Boltzmann kinetic equation using Poisson bracket (classical Hamilton equation) and Rindler Hamiltonian. Further, we treat the whole Universe as a statistical system with galaxies as the point particle constituents in large scale structure. Since the collisions of galaxies are very rare phenomena, we assume that the gas with the constituents as point galaxies satisfy Vlasov equation. Read More


The wave equation, describing the electron in a well extended along some line, can formally have the solution that becomes singular approaching this line. This solution does not exist in reality since it is not supported by a singular source. In processes of electron mass generation the singular electron density produces the singular correction to the expectation value of the Higgs field. Read More


A mathematical model (referred as $\Psi$ - model for convenience) has been developed, which allows describing certain class of micro- and macrosystems. $\Psi$ - model is based on continuum and quantum mechanics. $\Psi$ - model describes micro- and macrosystems, in which vector field of velocities of probability flows, charge, mass has specific spiral structure. Read More


The present work is a second in the series of investigation of the background dynamics in brane cosmology when dark energy is coupled to dark matter by a suitable interaction. Here dark matter is chosen in the form of perfect fluid with barotropic equation of state while a real scalar field with self interacting potential is chosen as dark energy. The scalar field potential is chosen as exponential or hyperbolic in nature and three different choices for the interaction between the dark species are considered. Read More


The principal new point is that ultra-high spin of the elementary particles makes Einstein's gravity so strong, that its influence to metric is shifted from Planck to the Compton scale! Compatibility of the Kerr-Newman (KN) gravity with quantum theory is achieved by implementation of the supersymmetric Higgs model without modification of the Einstein-Maxwell gravity. We consider the nonperturbative bag-like solution to supersymmetric generalized LG field model, which creates a flat and supersymmetric vacuum state inside the bag, forming the Compton zone for consistent work of quantum theory. The bag is deformable, and its shape is controlled by BPS bound, providing compatibility of the bag boundary with external gravitational and electromagnetic (EM) field. Read More


Cylindrical Couette flow is a subject where the main focus has long been on the onset of turbulence or, more precisely, the limit of stability of the simplest laminar flow. The theoretical framework of this paper is a recently developed action principle for hydrodynamics. It incorporates Euler-Lagrange equations that are in essential agreement with the Navier-Stokes equation, but applicable to the general case of a compressible fluid. Read More


In classical mechanics, a light particle bound by a strong elastic force just oscillates at high frequency in the region allowed by its initial position and velocity. In quantum mechanics, instead, the ground state of the particle becomes completely de-localized in the limit $m \to 0$. The harmonic oscillator thus ceases to be a useful microscopic physical model in the limit $m \to 0$, but its Feynman path integral has interesting singularities which make it a prototype of other systems exhibiting a "quantum runaway" from the classical configurations near the minimum of the action. Read More


Planck units are natural physical scales of mass, length and time, built with the help of the fundamental constants $\hbar, c, G$. The functional role of the constants used for the construction of Planck units is different. If the first two of them represent the limits of the action and the speed of light and underlie quantum mechanics and special relativity, the Newton's constant $G$ "only" fixes the absolute value of the gravitational forces. Read More


The implications of considering interaction between Chaplygin gas and a barotropic fluid with constant equation of state have been explored. The unique feature of this work is that assuming an interaction $Q \propto H\rho_d$ , analytic expressions for the energy density and pressure have been derived in terms of the Hypergeometric $_2\text{F}_1$ function. It is worthwhile to mention that an interacting Chaplygin gas model was considered in 2003 by Zhang and Zhu, nevertheless, analytic solutions for the continuity equations could not be determined assuming an interaction proportional to $H$ times the sum of the energy densities of Chaplygin gas and dust. Read More


The scalar-tensor theory of gravitation proposed by Mbelek and Lachi\`{e}ze-Rey has been shown to lead to a possible explanation of the forces measured in asymmetric resonant microwave cavities. However, in the derivation of the equations from the action principle some inconsistencies were observed, like the need no to vary the electromagnetic invariant in a scalar source term. Also, the forces obtained were too high, in view of reconsideration of the experiments originally reported and of newly published results. Read More


An alternative, scalar theory of gravitation has been proposed, based on a mechanism/interpretation of gravity as being a pressure force: Archimedes' thrust. In it, the gravitational field affects the physical standards of space and time, but motion is governed by an extension of the relativistic form of Newton's second law. This implies Einstein's geodesic motion for free particles only in a constant gravitational field. Read More


A compact four-dimensional manifold whose metric tensor has a positive determinant (named the "Euclid ball") is considered. The Euclid ball can be immersed in the Minkovskian space (which has the negative determinant) and can exist stably through the history of the universe. Since the Euclid ball has the same solution as the Schwarzschild black hole on its three-dimensional surface, an asymptotic observer can not distinguish them. Read More


Conformal symmetry and color confinement in the infrared regime of QCD are attributed to the global properties of a 4D space-time of a deSitter dS4 geometry which, according to the principle of deSitter special relativity, is viable outside the causal Minkowski light cone, where it reigns over the interactions involving the virtual gluon- and quark degrees of freedom of hadrons. Within this scenario, the conformal symmetry of QCD is a direct consequence of the conformal symmetry of the dS4 space- time, while the color confinement appears as a consequence of the innate charge neutrality of the unique closed space-like geodesic on this space, the three dimensional hypersphere S3, also being the unique dS4 sub-manifold suited as a stage for near rest-frame physics. In further making use of the principles of the mathematical discipline of potential theory, and postulating that fundamental interactions are defined by Green functions of Laplace operators on manifolds, taken here as the dS4 geodesics, a color-dipole potential has been derived on S3 whose magnitude, N_c\alpha_s is the product of the number of colors, N_c, and the strong coupling constant $\alpha_s$ in QCD, and pretty much as the amplitude, Z\alpha, of the Coulomb interaction following from QED. Read More


Quantum diagrams are the best language for Quantum Mechanics since they show not only a final result but also the physical process which leads to the result. The quantum correlation at a distance better known as the Einstein-Podolsky-Rosen paradox may be easily understood being depicted in the time-ordered quantum diagrams. In the diagrams one can clearly see what the so-called entangled quantum states really are and how they contribute to the violation of Bell inequality. Read More


In this article we provide a new class of interior solutions of a five dimensional compact star in Einstein Gauss-Bonnet (EGB) gravity within the framework of Finch-skea space time. The Exterior space time is described by the EGB schwarzschild solution. To check physically validity of our model we investigate various physical properties like causality of solutions, Energy conditions, mass radius relations, TOV equations etc. Read More


Many quantities are attributed a range of values that can apparently extend to infinity (on one side or both sides). In this respect, the definitions of their measurement units do not place any constraint to the maximum (or minimum) value for their validity. In general, that happens because those extreme values are far from being reached on the earth, or presently in experiments. Read More


Contemporary physics, both Classical and Quantum, requires a notion of inertial reference frames. However, how to find a physical inertial frame in reality where there always exist random weak forces? We suggest a description of the motion in non-inertial frames by means of inclusion of higher time derivatives. They may play a role of non-local hidden variables in a more general description complementing both classical and quantum mechanics. Read More


The \emph{Relativistic Schr\"odinger Theory} (RST) has been set up as an alternative form of particle theory. This theory obeys the fundamental symmetries which are required to hold for any meaningful theory: gauge and Lorentz covariance (RST can be formulated even over a pseudo-Riemannian space-time). But the question is now whether obeying those fundamental symmetries is sufficient for the practical success of a theory, i. Read More


The topologically nontrivial solution in Einstein-Dirac gravity with cosmological constant is obtained. The spacetime has the Hopf bundle as a spatial section. It is shown that the Hopf invariant is related to the spinor current density. Read More


The procedure commonly used in textbooks for determining the eigenvalues and eigenstates for a particle in an attractive Coulomb potential is not symmetric in the way the boundary conditions at $r=0$ and $r \rightarrow \infty$ are considered. We highlight this fact by solving a model for the Coulomb potential with a cutoff (representing the finite extent of the nucleus); in the limit that the cutoff is reduced to zero we recover the standard result, albeit in a non-standard way. This example is used to emphasize that a more consistent approach to solving the Coulomb problem in quantum mechanics requires an examination of the non-standard solution. Read More


We describe the neutrino flavor (e = electron, u = muon, t = tau) masses as m(i=e;u;t)= m + [Delta]mi with |[Delta]mij|/m < 1 and probably |[Delta]mij|/m << 1. The quantity m is the degenerate neutrino mass. Because neutrino flavor is not a quantum number, this degenerate mass appears in the neutrino equation of state. Read More


We investigate perfect fluid stars in $(2+1)$ dimension in pseudo spheroidal spacetime with the help of Vaidya-Tikekar metric where the physical $3$-space ($t=$ constant) is described by pseudo-spheroidal geometry. Here the spheroidicity parameter $a$, plays an important role for determining the properties of a compact star. In the present work a class of interior solutions corresponding to the Ba$\tilde{n}$ados-Teitelboim-Zanelli $(BTZ)$ exterior metric has been provided which describes a static circularly symmetric star with negative cosmological constant in equilibrium. Read More


New exact solutions of Einstein's field equations (EFEs) by assuming linear equation of state, $ p_r = \alpha (\rho - \rho_R) $ where $ p_r $ is the radial pressure and $ \rho_R $ is the surface density, are obtained on the background of a paraboloidal spacetime. By assuming estimated mass and radius of strange star candidate 4U 1820-30, various physical and energy conditions are used for estimating the range of parameter $ \alpha $. The suitability of the model for describing pulsars like PSR J1903+327, Vela X-1, Her X-1 and SAX J1804. Read More


Proton spin problem is given a new perspective with the proposition that spin is a topological invariant represented by a de Rham 3-period. The idea is developed generalizing Finkelstein-Rubinstein theory for Skyrmions/kinks to topological defects, and using nonabelian de Rham theorems. Two kinds of de Rham theorems are discussed applicable to matrix valued differential forms, and traces. Read More


A non-diagonal vielbein ansatz is applied to the $N$-dimension field equations of $f(T)$ gravity. An analytical vacuum solution is derived for the quadratic polynomial $f(T)=T+\epsilon T^2$ in the presence of a cosmological constant $\Lambda$. Since the induced metric has off diagonal components, that cannot be removed by a mere of a coordinate transformation, the solution has a rotating parameter. Read More


2016Dec
Affiliations: 1Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo, 2Ain Shams U., Cairo, 3Ain Shams U., Cairo

The assumption that the production of quark-antiquark pairs and their sequential string-breaking taking place through the event horizon of the color confinement determines freezeout temperature and gives a plausible interpretation of the thermal pattern of pp and AA collisions. When relating the black-hole electric charges to the baryon-chemical potentials it was found that the phenomenologically-deduced parameters from various particle ratios in the statistical thermal models agree well with the ones determined from the thermal radiation from charged black-hole. Accordingly, the resulting freezeout conditions, such as $s/T^3=7$ and $/=1~$GeV, are confirmed at finite chemical potentials, as well. Read More


In this paper we model a canonical acoustic thin shell wormhole (CATSW) in the framework of analogue gravity systems. In this model we apply cut and paste technique to join together two spherically symmetric, analogue canonical acoustic solutions, and compute the analogue surface density/surface pressure of the fluid using the Darmois Israel formalism. We study the stability analyses by using a linear barotropic fluid (LBF), chaplygin fluid (CF), logarithmic fluid (LogF), polytropic fluid (PF), and finally Van der Waals Quintessence (VDWQ). Read More


Sliding friction is ubiquitous in nature as are harmonic oscillators. However, when treating harmonic oscillators the effect of sliding friction is often neglected. Here, we propose a simple analytical model to include both viscous and sliding fiction in common harmonic oscillator equations, allowing to separate these different types of dissipation. Read More


We investigate and compare different representations of the Riesz derivative, which plays an important role in anomalous diffusion and space fractional quantum mechanics. In particular, we show that a certain representation of the Riesz derivative that is generally given as also valid for order alpha equals 1, behaves no differently than the other definition given in terms of its Fourier transform. In the light of this, we discuss the alpha goes to 1 limit of the space fractional quantum mechanics and its consistency. Read More


The metric of spherically symmetric ball of ideal liquid is considered in $G^2$- approximation with the help of theory of sources. Using the integral equations of this theory gives the exterior metric depending upon the radius of the ball of matter in some terms proportional to $G^2$.. Read More


In this work, according to the electromagnetic field tensor in the framework of generalized uncertainty principle (GUP), we obtain the Lorentz force and Faraday's law of induction in the presence of a minimal length. Also, the ponderomotive force and pomderomotive pressure in the presence of a measurable minimal length are found. Read More


The perfect Planck spectrum of the observed cosmic microwave background radiation indicates that our universe must be in thermal equilibrium. The dark sector of the universe should also be in the same equilibrium state with dark matter and dark energy coupled to each other and emits gravitational phonon blackbody radiation which is the main component of the cosmic background radiation. In the radiation-dominated era such gravitational radiation should be the majority species of the cosmic medium. Read More


We propose a new model of nonlinear electrodynamics with three parameters. Born-Infeld electrodynamics and exponential electrodynamics are particular cases of this model. The phenomenon of vacuum birefringence is studied. Read More


We describe the phenomenon of generation of an external field of forces from piezoelectric materials subjected to the application of electric fields or mechanical stress. The piezoelectric materials are shown as being capable of producing induction forces in external objects and we conclude that the nature of the forces generated are not originated from the traditional interactions. Further we specifically assert that the generation of forces by the piezoelectric materials is ruled by the hypothesis of preexisting condition of generalized quantum entanglement between the molecular structure of the material bulk and the surrounding environment. Read More


We reconsider the holographic dark energy (HDE) model with a slowly time varying $ c^2(z)$ parameter in the energy density, namely $\rho_D=3M_p^2 c^2(z)/L^2$, where $L$ is the IR cutoff and $z$ is the redshift parameter. As the system's IR cutoff we choose the Hubble radius and the Granda-Oliveros (GO) cutoffs. The latter inspired by the Ricci scalar curvature. Read More


A relativistic 4D string is described in the framework of the covariant quantum theory first introduced by Stueckelberg (1941) [1], and further developed by Horwitz and Piron (1973) [2], and discussed at length in the book of Horwitz (2015) [3]. We describe the space-time string using the solutions of relativistic harmonic oscillator [4]. We first study the problem of the discrete string, both classically and quantum mechanically, and then turn to a study of the continuum limit, which contains a basically new formalism for the quantization of an extended system. Read More


A constant (spacetime-independent) $q$-field may play a crucial role for the cancellation of Planck-scale contributions to the gravitating vacuum energy density. We now show that a small spacetime-dependent perturbation of the equilibrium $q$-field behaves gravitationally as a pressureless perfect fluid. This makes the fluctuating part of the $q$-field a candidate for the inferred dark-matter component of the present universe. Read More