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We show that kernel-based quadrature rules for computing integrals can be seen as a special case of random feature expansions for positive definite kernels, for a particular decomposition that always exists for such kernels. We provide a…

Machine Learning · Computer Science 2015-11-10 Francis Bach

The results of theoretical investigation of angular distributions of radiation from a relativistic electron passing through a thin crystal at a small angle to the crystal axis are presented. The electron trajectories in crystal were…

High Energy Physics - Phenomenology · Physics 2007-05-23 X. Artru , S. P. Fomin , N. F. Shul'ga

Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and…

High Energy Physics - Phenomenology · Physics 2012-06-13 C. Ditsche , M. Hoferichter , B. Kubis , U. -G. Meißner

The in-medium modification to the neutrino-nucleon scattering rate is calculated in the relativistic random phase approximation in the framework of a hadronic meson exchange model, in view of applications to neutrino transport in supernovae…

Nuclear Theory · Physics 2009-11-07 L. Mornas

We consider the stochastic differential equation on $\mathbb{R}^d$ given by $$ \, \mathrm{d}X_t = b(t,X_t) \, \mathrm{d}t + \, \mathrm{d} B_t, $$ where $B$ is a Brownian motion and $b$ is considered to be a distribution of regularity $ >…

Probability · Mathematics 2026-05-14 Nicolas Perkowski , Willem van Zuijlen

In this work a calculation of the cluster decomposable formalism for relativistic scattering as developed by Lindesay, Markevich, Noyes, and Pastrana (LMNP) is made for an ultra-light quantum model. After highlighting areas of the theory…

Nuclear Theory · Physics 2022-10-12 Marcus Alfred , James Lindesay

Multi-group method is an accepted technique for approximately solving the equation of radiative transfer. In this paper, group averaged transfer scattering cross sections, required for solving the equation of radiative transfer in a…

Plasma Physics · Physics 2010-08-31 J. Fiedler

Details are presented of an efficient formalism for calculating transmission and reflection matrices from first principles in layered materials. Within the framework of spin density functional theory and using tight-binding muffin-tin…

Materials Science · Physics 2015-06-25 K. Xia , M. Zwierzycki , M. Talanana , P. J. Kelly , G. E. W. Bauer

X-ray scattering patterns from emerging single particle experiments have commonly many missing or contaminated pixels. This complicates different analyses including projections on Fourier or other basis functions (for noise suppression,…

Data Analysis, Statistics and Probability · Physics 2014-11-19 Aliakbar Jafarpour

We simulate convection near the solar surface, where the continuum optical depth is of order unity. Hence, to determine the radiative heating and cooling in the energy conservation equation, we must solve the radiative transfer equation…

Astrophysics · Physics 2007-05-23 Robert Stein , Aake Nordlund

This work presents an efficient numerical method to evaluate the free energy density and associated thermodynamic quantities of (quasi) one-dimensional classical systems, by combining the transfer operator approach with a numerical…

Numerical Analysis · Mathematics 2021-03-09 Christian B. Mendl , Folkmar Bornemann

We present the implementation of a radiative transfer solver with coherent scattering in the new BIFROST code for radiative magneto-hydrodynamical (MHD) simulations of stellar surface convection. The code is fully parallelized using MPI…

Solar and Stellar Astrophysics · Physics 2017-11-08 W. Hayek , M. Asplund , M. Carlsson , R. Trampedach , R. Collet , B. V. Gudiksen , V. H. Hansteen , J. Leenaarts

We discuss possibilities of measurement of deeply virtual Compton scattering amplitudes via different asymmetries in order to access the underlying skewed parton distributions. Perturbative one-loop coefficient functions and two-loop…

High Energy Physics - Phenomenology · Physics 2009-10-31 A. V. Belitsky , D. Müller , L. Niedermeier , A. Schäfer

The illumination of an accretion disk around a black hole or neutron star by the central compact object or the disk itself often determines its spectrum, stability, and dynamics. The transport of radiation within the disk is in general a…

Astrophysics · Physics 2009-11-06 Dimitrios Psaltis

A numerical method to solve the direct scattering problem for the Zakharov-Shabat system associated to the initial value problem for the nonlinear Schroedinger equation is proposed. The method involves the numerical solution of Volterra…

Numerical Analysis · Mathematics 2015-02-17 Luisa Fermo , Cornelis van der Mee , Sebastiano Seatzu

We introduce the radiative transfer postprocessing code Subsweep. The code is based on the method of transport sweeps, in which the exact solution to the scattering-less radiative transfer equation is computed in a single pass through the…

Instrumentation and Methods for Astrophysics · Physics 2024-12-03 Toni Peter , Joseph S. W. Lewis , Ralf S. Klessen , Simon C. O. Glover , Guido Kanschat

A formalism is introduced for the non-perturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of light from two-dimensional penetrable rough surfaces. As an example, we apply this formalism to study the…

Optics · Physics 2012-05-03 Tor Nordam , Paul Anton Letnes , Ingve Simonsen

Background: Path integrals are a powerful tool for solving problems in quantum theory that are not amenable to a treatment by perturbation theory. Most path integral computations require an analytic continuation to imaginary time. While…

Nuclear Theory · Physics 2020-07-01 W. N. Polyzou , Ekaterina Nathanson

In this paper we extend a gradient estimate of R. Hamilton for positive solutions to the heat equation on closed manifolds to bounded positive solutions on complete, non-compact manifolds with $Rc \geq -Kg$. We accomplish this extension via…

Analysis of PDEs · Mathematics 2007-05-23 Brett Kotschwar

The formalism to describe the scattering of a weakly bound projectile nucleus by a heavy target is investigated, using the Uncorrelated Scattering Approximation. The main assumption involved is to neglect the correlation between the…

Nuclear Theory · Physics 2009-11-10 A. M. Moro , J. A. Caballero , J. Gomez-Camacho