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The propagation of light in a scattering medium is described as the motion of a special kind of a Brownian particle on which the fluctuating forces act only perpendicular to its velocity. This enforces strictly and dynamically the…

Disordered Systems and Neural Networks · Physics 2009-10-31 S. Anantha Ramakrishna , N. Kumar

We study the solution of the diffusion equation for Ultra-High Energy Cosmic Rays in the general case of an expanding universe, comparing it with the well known Syrovatsky solution obtained in the more restrictive case of a static universe.…

Astrophysics · Physics 2007-06-15 R. Aloisio , V. Berezinsky , A. Gazizov

The various distribution functions can encompass the diverse characteristics of the magnetospheric plasma of surrounding neutron stars in both hot and cold environments; however, the Maxwell-J\"uttner distribution is so far widely used to…

High Energy Astrophysical Phenomena · Physics 2025-05-02 M. Mousavi , J. Benáček

The problem of anomalous diffusion in momentum space is considered for plasma-like systems on the basis of a new collision integral, which is appropriate for consideration of the probability transition function (PTF) with long tails in…

Statistical Mechanics · Physics 2015-05-18 S. A. Trigger , W. Ebeling , G. J. F. van Heijst , P. P. J. M. Schram , I. M. Sokolov

We discuss metric perturbations of the relativistic diffusion equation around the homogeneous Juttner equilibrium of massless particles in a homogeneous expanding universe. The metric perturbation describes matter distribution and the…

General Relativity and Quantum Cosmology · Physics 2015-02-27 Z. Haba

We study a relativistic diffusion equation on the Riemannian phase space defined by Franchi and Le Jan. We discuss stochastic Ito (Langevin) differential equations (defining the diffusion) as a perturbation by noise of the geodesic…

General Relativity and Quantum Cosmology · Physics 2015-05-14 Z. Haba

We analyze one-dimensional photonic superlattices which alternate layers of air and a left-handed material. We assume Drude-type dispersive responses for the dielectric permittivity and magnetic permeability of the left-handed material.…

Other Condensed Matter · Physics 2015-05-13 E. Reyes-Gomez , A. Bruno-Alfonso , S. B. Cavalcanti , C. A. A. de Carvalho , L. E. Oliveira

The problem of anomalous diffusion in the momentum space is considered on the basis of the appropriate probability transition function (PTF). New general equation for description of the diffusion of heavy particles in the gas of the light…

Statistical Mechanics · Physics 2015-05-13 S. A. Trigger

The Markovian diffusion theory in the phase space is generalized within the framework of the general theory of relativity. The introduction of moving orthonormal frame vectors both for the position as well the velocity space enables to…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Joachim Herrmann

The present work describes some extensions of an approach, originally developed by V.V. Yatsyk and the author, for the theoretical and numerical analysis of scattering and radiation effects on infinite plates with cubically polarized…

Mathematical Physics · Physics 2026-02-04 Lutz Angermann

We investigate the diffusion of particles in an attractive one-dimensional potential that grows logarithmically for large $|x|$ using the Fokker-Planck equation. An eigenfunction expansion shows that the Boltzmann equilibrium density does…

Statistical Mechanics · Physics 2015-05-28 A. Dechant , E. Lutz , E. Barkai , D. A. Kessler

By means of a particle model that includes interactions only via the local particle concentration, we show that hyperballistic diffusion may result. This is done by findng the exact solution of the corresponding non-linear diffusion…

Statistical Mechanics · Physics 2020-12-08 Eirik G. Flekkøy , Alex Hansen , Beatrice Baldelli

This paper summarizes the limits on propagation of ultra high energy particles in the Universe, set up by their interactions with cosmic background of photons and neutrinos. By taking into account cosmic evolution of these backgrounds and…

High Energy Astrophysical Phenomena · Physics 2018-01-24 R. Ruffini , G. V. Vereshchagin , S. -S. Xue

In this paper we review the extragalactic propagation of ultrahigh energy cosmic-rays (UHECR). We present the different energy loss processes of protons and nuclei, and their expected influence on energy evolution of the UHECR spectrum and…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Denis Allard

The propagator of the discrete Schr\"odinger equation is computed and its properties are revealed through a Feynman path summation in discrete space. Initial data problems such as diffraction in discrete space and continuous time are…

Quantum Physics · Physics 2012-11-01 Emerson Sadurní

In this paper the fields generated by an electric dipole and a gravitational quadrapole are shown to propagate superluminally in the nearfield of the source and reduce to the speed of light as the fields propagate into the farfield. A…

General Physics · Physics 2007-05-23 William D. Walker

We discuss a simple approach to solve the transport equation for high-energy neutrinos in media of any thickness. We present illustrative results obtained with some specific models for the initial spectra of muon neutrinos and antineutrinos…

High Energy Physics - Phenomenology · Physics 2014-11-17 V. A. Naumov , L. Perrone

The linear Boltzmann equation for elastic and/or inelastic scattering is applied to derive the distribution function of a spatially homogeneous system of charged particles spreading in a host medium of two-level atoms and subjected to…

Statistical Mechanics · Physics 2009-11-13 A. Rossani , A. M. Scarfone

The coupled system of Boltzman equations for the interacting system of electrons, positrons and photons in high external electric, E, and arbitrary magnetic, H, fields is solved. The consideration is made under the conditions of arbitrary…

Quantum Physics · Physics 2007-05-23 T. M. Gassym

Tightly bound excitons in monolayer semiconductors represent a versatile platform to study two-dimensional propagation of neutral quasiparticles. Their intrinsic properties, however, can be severely obscured by spatial energy fluctuations…