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This paper studies cosmic ray (CR) transport in magneto hydrodynamic (MHD) turbulence. CR transport is strongly dependent on the properties of the magnetic turbulence. We perform test particle simulations to study the interactions of CR…

High Energy Astrophysical Phenomena · Physics 2022-02-23 Snehanshu Maiti , Kirit Makwana , Heshou Zhang , Huirong Yan

A diffusion Monte Carlo algorithm is introduced that can determine the correct nodal structure of the wave function of a few-fermion system and its ground-state energy without an uncontrolled bias. This is achieved by confining signed…

Computational Physics · Physics 2020-02-05 Alexander A. Kunitsa , So Hirata

The Diffusion Monte Carlo method with constant number of walkers, also called Stochastic Reconfiguration as well as Sequential Monte Carlo, is a widely used Monte Carlo methodology for computing the ground-state energy and wave function of…

Statistics Theory · Mathematics 2024-12-09 Michel Caffarel , Pierre del Moral , Luc de Montella

The "backward simulation" of a stochastic process is defined as the stochastic dynamics that trace a time-reversed path from the target region to the initial configuration. If the probabilities calculated by the original simulation are…

Data Analysis, Statistics and Probability · Physics 2019-01-29 Shinichi Takayanagi , Yukito Iba

Possible formulations of the problem of cosmic rays acceleration in the interstellar galactic medium are considered with the use of fractional differential equations. The applied technique has been physically justified. A Fermi result has…

Astrophysics of Galaxies · Physics 2011-05-19 V. V. Uchaikin

We offer a new proposal for the Monte Carlo treatment of many-fermion systems in continuous space. It is based upon Diffusion Monte Carlo with significant modifications: correlated pairs of random walkers that carry opposite signs;…

Condensed Matter · Physics 2009-10-31 M. H. Kalos , Francesco Pederiva

The standard way to model the cosmic ray solar modulations is via the Parker equation, that is as the effect of diffusion in the turbulent magnetic of an expanding solar wind. Calculations performed with this method that do not include a…

High Energy Astrophysical Phenomena · Physics 2014-08-05 Paolo Lipari

Neutrino-matter interactions play an important role in the post-merger evolution of neutron star-neutron star and black hole-neutron star mergers. Most notably, they determine the properties of the bright optical/infrared transients…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Francois Foucart , Matthew D. Duez , Lawerence E. Kidder , Ronny Nguyen , Harald P. Pfeiffer , Mark A. Scheel

In this work, we demonstrate how differentiable stochastic sampling techniques developed in the context of deep Reinforcement Learning can be used to perform efficient parameter inference over stochastic, simulation-based, forward models.…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-09 Benjamin Horowitz , ChangHoon Hahn , Francois Lanusse , Chirag Modi , Simone Ferraro

We study the Monte Carlo method for solving a linear system of the form $x = H x + b$. A sufficient condition for the method to work is $\| H \| < 1$, which greatly limits the usability of this method. We improve this condition by proposing…

Numerical Analysis · Computer Science 2016-08-17 Tao Wu , David F. Gleich

The secondary-to-primary ratios are unique tools to investigate cosmic ray propagation mechanisms. In this work, we use the latest data of deuteron-to-helium~4 ratio and helium~3-to-helium~4 ratio measured by PAMELA combined with other…

High Energy Astrophysical Phenomena · Physics 2018-12-31 Juan Wu , Chen Huan

We propose a sampling-based framework for finite-horizon trajectory and policy optimization under differentiable dynamics by casting controller design as inference. Specifically, we minimize a KL-regularized expected trajectory cost, which…

Machine Learning · Computer Science 2026-05-12 Heng Yang

We have developed a novel computer code designed to follow the evolution of cosmic-ray modified shocks, including the full momentum dependence of the particles for a realistic diffusion coefficient model. In this form the problem is…

Astrophysics · Physics 2009-10-31 Hyesung Kang , T. W. Jones , R. J. LeVeque , K. M. Shyue

The mechanism driving core-collapse supernovae is sensitive to the interplay between matter and neutrino radiation. However, neutrino radiation transport is very difficult to simulate, and several radiation transport methods of varying…

High Energy Astrophysical Phenomena · Physics 2017-10-11 Sherwood Richers , Hiroki Nagakura , Christian D. Ott , Joshua Dolence , Kohsuke Sumiyoshi , Shoichi Yamada

Conventional cosmic-ray propagation models usually assume an isotropic diffusion coefficient to account for the random deflection of cosmic rays by the turbulent interstellar magnetic field. Such a picture is very successful in explaining…

High Energy Astrophysical Phenomena · Physics 2020-03-24 Wei Liu , Su-jie Lin , Hong-bo Hu , Yi-qing Guo , Ai-feng Li

We report calculations of cosmic-ray proton, nuclei, antiproton, electron and positron energy spectra within a "two-halo model" of diffusive transport. The two halos represent a simple, physically consistent generalization of the standard…

High Energy Astrophysical Phenomena · Physics 2015-10-20 Nicola Tomassetti

A new code for evaluation of light absorption and scattering by interstellar dust grains is presented. The radiative transfer problem is solved using ray-tracing algorithm in a self-consistent and highly efficient way. The code demonstrates…

Astrophysics · Physics 2007-05-23 D. Semionov , V. Vansevicius

In recent years efficient algorithms have been developed for the numerical computation of relativistic single-particle path integrals in quantum field theory. Here, we adapt this "worldline Monte Carlo" approach to the standard problem of…

Hamiltonian Monte Carlo (HMC) sampling methods provide a mechanism for defining distant proposals with high acceptance probabilities in a Metropolis-Hastings framework, enabling more efficient exploration of the state space than standard…

Methodology · Statistics 2014-05-13 Tianqi Chen , Emily B. Fox , Carlos Guestrin

The Monte Carlo technique is used to calculate electrical as well as thermoelectric transport properties across thin film heterostructures. We study a thin InGaAsP barrier layer sandwiched between two InGaAs contact layers, when the barrier…

Materials Science · Physics 2009-11-11 Mona Zebarjadi , Ali Shakouri , Keivan Esfarjani