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Ultrafast scattering using X-rays or electrons is an emerging method to obtain structure dynamics at the atomic length and time scales. However, directly resolving in real-space atomic motions is inherently limited by the finite detector…

Atomic Physics · Physics 2023-02-09 Adi Natan

Accurate accounting of particle number and 4-momentum in radiative transfer may be facilitated by the use of transport equations that allow transparent conversion between volume and surface integrals in both spacetime and momentum space.…

Astrophysics · Physics 2016-11-09 Christian Y. Cardall

We discuss a recent computation of Compton scattering on the deuteron at photon energies of order the pion mass. An interaction kernel is computed in baryon chiral perturbation theory and sewn to phenomenological deuteron wave functions. As…

Nuclear Theory · Physics 2007-05-23 Silas R. Beane

Coherent, continuous spatial representations are critical for synthesizing physical and perceptual phenomena into a single representational space. Radial basis kernels provide a path forward for this type of distributed representation. In…

Machine Learning · Computer Science 2026-05-12 Jakeb Chouinard

Selecting optimal kernels for regression in physical systems remains a challenge, often relying on trial-and-error with standard functions. In this work, we establish a mathematical correspondence between support vector machine kernels and…

Quantum Physics · Physics 2026-01-05 Nan-Hong Kuo , Renata Wong

It has now become possible to study directly, via numerical simulation, the evolution of relativistic, radiation-dominated flows around compact objects. With this in mind we set out explicitly covariant forms of the radiative transfer…

High Energy Astrophysical Phenomena · Physics 2020-01-29 Shane W. Davis , Charles F. Gammie

The theory of incoherent nuclear resonant scattering of synchrotron radiation accompanied by absorption or emission of phonons in a crystal lattice is developed. The theory is based on the Maxwell's equations and time-dependent quantum…

Materials Science · Physics 2007-05-23 V. G. Kohn , A. I. Chumakov

We present a method to reconstruct the dielectric susceptibility (scattering potential) of an inhomogeneous scattering medium, based on the solution to the inverse scattering problem with internal sources. We employ the theory of…

Numerical Analysis · Mathematics 2024-07-18 Yakun Dong , Kamran Sadiq , Otmar Scherzer , John C. Schotland

Working within the framework of the covariant perturbation theory, we obtain the coincidence limit of the heat kernel of an elliptic second order differential operator that is applicable to a large class of quantum field theories. The basis…

High Energy Physics - Theory · Physics 2008-12-18 Yuri V. Gusev

In this paper we present the spectrum of synchro-curvature self-Compton (SCSC) radiation of relativistic electrons with a power-law distribution of Lorentz factors. We find that the resulting spectrum is significantly different from that of…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Bo Zhang , Zi-Gao Dai

The Heat Kernel Method is applied to the constituent quark model. We calculate the effect of thermal quark fluctuations on the meson action and the resulting quark condensate and pi pi-scattering amplitude at finite temperature. The quarks…

High Energy Physics - Phenomenology · Physics 2009-10-30 B. -J. Schaefer , H. -J. Pirner

Convolution is an important tool in the construction of positive definite kernels on a manifold. This contribution provides conditions on an $L^2$-positive definite and zonal kernel on the unit sphere of $\mathbb{C}^q$ in order that the…

Classical Analysis and ODEs · Mathematics 2015-02-16 Victor S. Barbosa , Valdir A. Menegatto

The electromagnetic radiation of a rotating relativistic electron layers is studied numerically using particle-in-cell simulation. The results of the simulation confirm all relevant scaling properties predicted by theoretical models. These…

Astrophysics · Physics 2007-05-23 Bjoern S. Schmekel

The quantum electrodynamical (QED) process of Compton scattering in strong magnetic fields is commonly invoked in atmospheric and inner magnetospheric models of x-ray and soft gamma-ray emission in high-field pulsars and magnetars. A major…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Peter L. Gonthier , Matthew G. Baring , Matthew T. Eiles , Zorawar Wadiasingh , Caitlin A. Taylor , Catherine J. Fitch

Scatter processes of photons lead to blurring of images produced by CT (computed tomography) or CBCT (cone beam computed tomography) in the KV domain or portal imaging in the MV domain (KV: kilovolt age, MV: megavoltage). Multiple scatter…

Medical Physics · Physics 2015-06-11 W. Ulmer

Nucleon generalized polarizabilities are investigated within a relativistic framework, defining such quantities through a Lorentz covariant multipole expansion of the amplitude for virtual Compton scattering. The key physical ingredients in…

Nuclear Theory · Physics 2016-09-08 B. Pasquini , G. Salme`

This paper investigates high-energy hadron-hadron scattering utilizing AdS/QCD correspondence, gravitational form factors, and the Brower-Polchinski-Strassler-Tan pomeron exchange kernel. We use the configurational complexity to estimate…

Nuclear Theory · Physics 2025-03-19 G. Karapetyan

Many scientific problems require identifying a small set of covariates that are associated with a target response and estimating their effects. Often, these effects are nonlinear and include interactions, so linear and additive methods can…

Computation · Statistics 2022-12-02 Raj Agrawal , Tamara Broderick

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

In this work, the concept of quasi-type Kernel polynomials with respect to a moment functional is introduced. Difference equation satisfied by these polynomials along with the criterion for orthogonality conditions are discussed. The…

Spectral Theory · Mathematics 2023-01-31 Vikash Kumar , A. Swaminathan