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We study power law inflation in the context of non-minimally coupled to the scalar curvature. We analyze the inflationary solutions under an exact analysis and also in the slow roll approximation. In both solutions, we consider the recent…

General Relativity and Quantum Cosmology · Physics 2015-08-06 Sergio del Campo , Carlos Gonzalez , Ramon Herrera

Based upon the rate equations for the photon distribution function obtained in the previous paper, we study the inverse Compton scattering process for high-energy nonthermal electrons. Assuming the power-law electron distribution, we find a…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-06 Satoshi Nozawa , Yasuharu Kohyama , Naoki Itoh

We investigate relativistic flows after a shock wave generated in a star arrives at the surface. First, the sphericity effect is involved through a successive approximation procedure by adding correction terms to an already known…

Astrophysics · Physics 2008-11-26 Reina Kikuchi , Toshikazu Shigeyama

When observations are independent, formulae and software are readily available to plan and design studies of appropriate size and power to detect important associations. When observations are correlated or clustered, results obtained from…

Applications · Statistics 2021-03-15 David M. Thompson

Velocity of a deeply non-relativistic particle can change during its acceleration inside an RF cavity significantly enough to cause a deviation of the energy gain from a linear model. This paper derives formulae for corrections to the…

Accelerator Physics · Physics 2021-07-29 Alexander Shemyakin

The dynamical reaction of the particles accelerated at a shock front by the first order Fermi process can be determined within kinetic models that account for both the hydrodynamics of the shocked fluid and the transport of the accelerated…

Astrophysics · Physics 2009-11-11 P. Blasi , S. Gabici , G. Vannoni

We have modeled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parameterizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow…

High Energy Astrophysical Phenomena · Physics 2015-07-15 Donald C. Warren , Donald C. Ellison , Andrei M. Bykov , Shiu-Hang Lee

While collisionless plasmas are ubiquitously present near astrophysical compact objects, the impact that their composition has on the high-energy emission is presently unknown. We present the first investigation of particle-acceleration…

High Energy Astrophysical Phenomena · Physics 2026-04-09 Claudio Meringolo , Mario Imbrogno , Alejandro Cruz-Osorio , Sergio Servidio , Luciano Rezzolla

For the first time, the energy diffusion approximation is confronted at the percent level with the exact numerical modeling of thermal decay of a metastable state. The latter is performed using the quasistationary decay rates resulting from…

Nuclear Theory · Physics 2019-08-13 Igor I. Gontchar , Maria V. Chushnyakova

We estimate the effects of non-perturbative physics on the differential distributions of infrared- and collinear-safe $e^+e^-$ event shape variables, by extending the notion of an infrared-regular effective strong coupling, which accounts…

High Energy Physics - Phenomenology · Physics 2009-10-30 Yu. L. Dokshitzer , B. R. Webber

We propose a kinetic equation for a special kind of acceleration: chaotic gun effect. Then we infer a distribution function which can depict the instability condition. With this distribution function we derive the power spectrum of the…

High Energy Astrophysical Phenomena · Physics 2009-02-17 Gheorghe Dumitrescu

Lattice growth models where uncorrelated random deposition competes with some aggregation dynamics that generates correlations are studied with rates of the correlated component decreasing as a power law. These models have anomalous…

Statistical Mechanics · Physics 2013-02-05 Fabio D. A. Aarao Reis

Relativistic shocks accelerate particles by the first order Fermi mechanism. These particles then emit synchrotron emission in the post shock gas. We have developed a numerical code which integrates the relativistic Euler equations for…

Astrophysics · Physics 2009-11-06 T. P. Downes , P. Duffy , S. Komissarov

The first-order cosmic ray acceleration at ultrarelativistic shocks is investigated using the Monte Carlo method. We apply a method of discrete particle momentum scattering as a model of particle pitch angle diffusion to reproduce highly…

Astrophysics · Physics 2007-05-23 J. Bednarz

Perpendicular shocks are shown to be rapid particle accelerators that perform optimally when the ratio $u_{\rm s}$ of the shock speed to the particle speed roughly equals the ratio $1/\eta$ of the scattering rate to the gyro frequency. We…

High Energy Astrophysical Phenomena · Physics 2015-08-18 Makoto Takamoto , John G. Kirk

In nucleus-nucleus collisions, high-pt electron spectra depend on the medium modified fragmentation of their massive quark parents, thus giving novel access to the predicted mass hierarchy of parton energy loss. Here we calculate these…

High Energy Physics - Phenomenology · Physics 2011-01-25 N. Armesto , M. Cacciari , A. Dainese , C. A. Salgado , U. A. Wiedemann

Prescriptions for electron injection into the diffusive shock acceleration process are required in many practical considerations of cosmic-ray astrophysics, particularly in modeling of the synchrotron emission of astrophysical sources. In…

High Energy Astrophysical Phenomena · Physics 2021-01-01 Bojan Arbutina , Vladimir Zeković

When factorized approximations are used for variational inference (VI), they tend to underestimate the uncertainty -- as measured in various ways -- of the distributions they are meant to approximate. We consider two popular ways to measure…

Machine Learning · Statistics 2023-05-29 Charles C. Margossian , Lawrence K. Saul

Relativistic shocks are considered efficient accelerators of charged particles and play crucial roles in high-energy astrophysical phenomena, such as gamma-ray bursts and pulsar winds. This study focuses on positron accelerations in…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Shori Arai , Yosuke Matsumoto

Variational Inference makes a trade-off between the capacity of the variational family and the tractability of finding an approximate posterior distribution. Instead, Boosting Variational Inference allows practitioners to obtain…

Machine Learning · Computer Science 2021-05-20 Gideon Dresdner , Saurav Shekhar , Fabian Pedregosa , Francesco Locatello , Gunnar Rätsch