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Divergences that occur in density matrices of decay and scattering processes are shown to be regularized by tracing and unitarity or the optical theorem. These divergences are regularized by the lifetime of the decaying particle or the…

High Energy Physics - Phenomenology · Physics 2024-06-13 Shanmuka Shivashankara , Patti Rizzo , Nicole Cafe

Charged particles in a magnetosphere are spontaneously attracted to a planet while increasing their kinetic energy via inward diffusion process. A constraint on particles' micro-scale adiabatic invariants restricts the class of motions…

Plasma Physics · Physics 2016-11-08 Y. Ushida , Y. Kawazura , N. Sato , Z. Yoshida

Entropy in thermodynamics is an extensive quantity, whereas standard methods in statistical mechanics give rise to a non-extensive expression for the entropy. This discrepancy is often seen as a sign that basic formulas of statistical…

History and Philosophy of Physics · Physics 2012-09-06 Dennis Dieks

One of the few accepted dynamical foundations of non-additive "non-extensive") statistical mechanics is that the choice of the appropriate entropy functional describing a system with many degrees of freedom should reflect the rate of growth…

Statistical Mechanics · Physics 2017-09-22 Nikolaos Kalogeropoulos

The entanglement entropy of a pure quantum state of a bipartite system is defined as the von Neumann entropy of the reduced density matrix obtained by tracing over one of the two parts. Critical ground states of local Hamiltonians in one…

Strongly Correlated Electrons · Physics 2016-09-08 Eduardo Fradkin

On the basis of the balance equations for energy-momentum, spin, particle and entropy density, an approach is considered which represents a comparatively general framework for special- and general-relativistic continuum thermodynamics. In…

General Relativity and Quantum Cosmology · Physics 2009-11-13 W. Muschik , H. -H. v. Borzeszkowski

The most rigorous physical description of non-equilibrium gas dynamics is rooted in the numerical solution of the Boltzmann equation. Yet, the large number of degrees of freedom and the wide range of both spatial and temporal scales render…

Computational Physics · Physics 2024-10-25 Anthony Chang , Narendra Singh , Marco Panesi

We prove that the gravitational binding energy {\Omega} of a self gravitating system described by a mass density distribution {\rho}(x) admits an upper bound B[{\rho}(x)] given by a simple function of an appropriate, non-additive Tsallis'…

Statistical Mechanics · Physics 2015-05-20 C. Vignat , A. Plastino , A. R. Plastino

We present an analysis of two thermodynamic techniques for determining equilibria of self-gravitating systems. One is the Lynden-Bell entropy maximization analysis that introduced violent relaxation. Since we do not use the Stirling…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Eric I. Barnes , Liliya L. R. Williams

We consider a system composed of a fixed number of particles with total energy smaller or equal to some prescribed value. The particles are non-interacting, indistinguishable and distributed over fixed number of energy levels. The energy…

Probability · Mathematics 2021-03-23 Tomasz M. Łapiński

Deformation of material lines drives transport and dissipation in many industrial and natural flows. Here we report an exact Eulerian formula for the stretching rate of a material line, also known as the topological entropy, in a prototype…

Fluid Dynamics · Physics 2024-12-16 Amal Manoharan , Sai Subramanian , Ashwin Joy

Turbulence may appear as a complex process with a multitude of scales and flow patterns, but still obeys simple physical principles such as the conservation of momentum, of energy, and the maximum entropy principle. The latter states that…

Fluid Dynamics · Physics 2019-04-23 T. -W. Lee

We study the thermodynamic parameters like entropy, energy etc. of a box of gas made up of indistinguishable particles when the box is kept in various static background spacetimes having a horizon. We compute the thermodynamic variables…

General Relativity and Quantum Cosmology · Physics 2011-04-07 Sanved Kolekar , T. Padmanabhan

The dynamics of molecular collisions in a macroscopic body are encoded by the parameter Thermodynamic entropy - a statistical measure of the number of molecular configurations that correspond to a given macrostate. Directionality in the…

Populations and Evolution · Quantitative Biology 2020-05-22 Lloyd Demetrius , Christian Wolf

The bulk viscosity of cosmological fluid and the creation of cold dark matter both result in the generation of irreversible entropy (related to dissipative processes) in a homogeneous and isotropic universe. To consider such effects, the…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-16 Nobuyoshi Komatsu , Shigeo Kimura

A completely new approach to the problem of energy distribution in statistical mechanics is developed that results in a general, combinatorial formula for the density of states. Relying on the approach the energy equipartition principle is…

Statistical Mechanics · Physics 2012-05-22 Agata Fronczak

Prompted by the realisation that the statistical entropy of an ideal gas in the micro-canonical ensemble should not fluctuate or change over time, the meaning of the H-theorem is re-interpreted from the perspective of information theory in…

General Physics · Physics 2013-01-09 David Sands , Jeremy Dunning-Davies

Surface topography governs tribological performance, yet conventional parameters describe either amplitude statistics or spectral content in isolation. We introduce a scale-dependent framework that represents surface height and directional…

Signal Processing · Electrical Eng. & Systems 2026-02-24 Boris Brodmann , Matthias Eifler

What is the probability that all the gas in a box accumulates in the same half of this box? Though amusing, this question underlies the fundamental problem of density fluctuations at equilibrium, which has profound implementations in many…

Statistical Mechanics · Physics 2014-04-25 Denis Michel

We consider the magnetic Lorentz gas proposed by Bobylev et al. [4], which describes a point particle moving in a random distribution of hard-disk obstacles in $\mathbb{R}^2$ under the influence of a constant magnetic field perpendicular to…

Mathematical Physics · Physics 2024-12-17 Alessia Nota , Dominik Nowak , Chiara Saffirio