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Solutions of stationary Fokker-Planck equations in the narrow beam regime are commonly approximated by either ballistic linear transport or by a Fermi pencil-beam equation. We present a rigorous approximation analysis of these three models…

Analysis of PDEs · Mathematics 2020-06-09 Guillaume Bal , Benjamin Palacios

The long-wavelength, weak-dispersion limit of the discrete nonlinear Schr\"odinger equation with long-range dispersion is analytically considered. This continuum approximation is carried out irrespective of the dispersion range and hence…

Pattern Formation and Solitons · Physics 2007-05-23 Alain M. Dikandé

Consistent quantum formalism based on the localized basis of the Wannirer functions in Heisenberg and Schrodinger pictures to describe propagation of electromagnetic field in a three dimensional media including diffraction is presented. In…

Quantum Physics · Physics 2015-06-26 V. N. Gorbachev , A. I. Zhiliba

Using a so-called hemispherical model we derive a general transport equation for cosmic ray and thermal particles scattered in pitch angle by magnetic inhomogeneities in a moving collisionless plasma. The weak scattering through 90 degrees…

Astrophysics · Physics 2009-11-11 V. N. Zirakashvili

We discuss the unitary quantum dynamics of the Dicke model (spin and oscillator coupled). A suitable quasiprobabilty representing the quantum state turns out to obey a Fokker-Planck equation, with drift terms representing the underlying…

Quantum Physics · Physics 2015-06-04 Alexander Altland , Fritz Haake

The stationary distribution of a fully chaotic system typically exhibits a fractal structure, which dramatically changes if the dynamical equations are even slightly modified. Perturbative techniques are not expected to work in this…

Chaotic Dynamics · Physics 2017-06-26 Jeffrey M. Heninger , Domenico Lippolis , Predrag Cvitanovic

A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in…

Optics · Physics 2015-06-11 T. Hansson , E. Wallin , G. Brodin , M. Marklund

We investigate the Cauchy problem and the diffusion asymptotics for a spatially inhomogeneous kinetic model associated to a nonlinear Fokker-Planck operator. We derive the global well-posedness result with instantaneous smoothness effect,…

Analysis of PDEs · Mathematics 2024-03-13 Francesca Anceschi , Yuzhe Zhu

We describe quantum-field-theoretical (QFT) techniques for mapping quantum problems onto c-number stochastic problems. This approach yields results which are identical to phase-space techniques [C.W. Gardiner, {\em Quantum Noise} (1991)]…

Statistical Mechanics · Physics 2007-05-23 L. I. Plimak , M. Fleischhauer , M. K. Olsen , M. J. Collett

A relativistic bounce-averaged quasilinear diffusion equation is derived to describe stochastic particle transport associated with arbitrary-frequency electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for the…

Space Physics · Physics 2009-11-10 Alain J. Brizard , Anthony A. Chan

We obtain new exact classes of solutions for the nonlinear fractional Fokker-Planck-like equation partial_t rho = partial_x{D(x) partial^{mu -1}_x rho^{nu} - F(x) rho} by considering a diffusion coefficient D = D|x|^{-theta} (theta in R and…

Statistical Mechanics · Physics 2009-11-07 E. K. Lenzi , L. C. Malacarne , R. S. Mendes , I. T. Pedron

Employing the well-known unitary equivalence between Fokker-Planck operators and Schr\"odinger Hamiltonians, we compute the quasi-normal-mode spectrum of ultrarelativistic kinetic theories with momentum-space diffusion. We show that the…

Nuclear Theory · Physics 2026-01-28 Lorenzo Gavassino

This paper extends the study of the quantum dissipative effects of a cosmological scalar field by taking into account the cosmic expansion and contraction. Cheung, Drewes, Kang and Kim calculated the effective action and quantum dissipative…

High Energy Physics - Theory · Physics 2024-07-18 Hui Xu , Lei Ming , Yeuk-Kwan E. Cheung

The pion structure function is investigated in a simple model, where the pion and its constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi -> gamma* pi scattering…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. P. Lansberg , F. Bissey , J. R. Cudell , J. Cugnon , M. Jaminon , P. Stassart

The Fokker-Planck equation for the probability $f(r,t)$ to find a random walker at position $r$ at time $t$ is derived for the case that the the probability to make jumps depends nonlinearly on $f(r,t)$. The result is a generalized form of…

Statistical Mechanics · Physics 2008-08-20 James F. Lutsko , Jean Pierre Boon

The free-space transfer of high-fidelity optical signals between remote locations has many applications, including both classical and quantum communication, precision navigation, clock synchronization, etc. The physical processes that…

Quantum Physics · Physics 2017-07-21 D. Vasylyev , A. A. Semenov , W. Vogel

We analyze the tomographic representation for the Friedmann-Robertson-Walker (FRW) model within the Loop Quantum Cosmology framework. We focus on the Wigner quasi-probability distributions associated with Gaussian and Schr\"odinger cat…

General Relativity and Quantum Cosmology · Physics 2021-04-21 Jasel Berra-Montiel , Alberto Molgado

We complement previous studies of an ion coupled with an optical cavity in the dispersive regime, for a model which exhibits bistability of different configurations in the semiclassical description. Our approach is based on a truncated…

Quantum Physics · Physics 2023-03-31 Alan Kahan , Leonardo Ermann , Marcos Saraceno , Cecilia Cormick

A new analytically and numerically manageable model collision operator is developed specifically for turbulence simulations. The like-particle collision operator includes both pitch-angle scattering and energy diffusion and satisfies the…

Plasma Physics · Physics 2009-02-02 I. G. Abel , M. Barnes , S. C. Cowley , W. Dorland , A. A. Schekochihin

The propagation of cosmic rays can be described as a diffusive motion in most galactic environments. High-energy gamma-rays measured by Fermi have allowed inference of a gradient in the cosmic-ray density and spectral energy behavior in the…

High Energy Astrophysical Phenomena · Physics 2021-10-14 J. Dörner , P. Reichherzer , L. Merten , J. Becker Tjus , H. Fichtner , M. J. Pueschel , E. G. Zweibel