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A universal numerical method is developed for the investigation of magnetic neutron scattering. By applying the pseudospectral-time-domain (PSTD) algorithm to the spinor version of the Schr\"odinger equation, the evolution of the spin-state…

Quantum Physics · Physics 2024-12-31 Kun Chen

We present a novel method for including the impact of massive neutrinos in cold dark matter N-body simulations. Our approach is compatible with widely employed Newtonian N-body codes and relies on only three simple modifications. First, we…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-05 Pol Heuschling , Christian Partmann , Christian Fidler

Bearing in mind the application to the collapsar models of gamma-ray bursts (GRBs), we develop a numerical scheme and code for estimating the deposition of energy and momentum due to the neutrino pair annihilation ($\nu + {\bar \nu}…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Seiji Harikae , Kei Kotake , Tomoya Takiwaki , Yu-ichiro Sekiguchi

This thesis focuses on the application of numerical relativity methods to the solutions of problems in strong gravity. Our goal is the study of mergers of compact objects in the strong field regime where non-linear dynamics manifest and…

General Relativity and Quantum Cosmology · Physics 2024-08-02 Llibert Aresté Saló

Next-generation gravitational wave detectors are expected to increase their sensitivity in the kHz band where binary neutron star remnants are expected to emit. In this context, robust predictions of oscillation modes of the post-merger…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Gaël Servignat , Jérôme Novak

In physics, accurately modeling large-scale phenomena such as core-collapse supernovae, (CCSN), and neutron star mergers are computationally challenging and require solving large sets of partial and ordinary differential equations.…

High Energy Astrophysical Phenomena · Physics 2024-09-06 Raghav Chari

We develop a "hybrid approximative scheme" in the framework of the post-Newtonian approximation for computing general-relativistic polytropic models simulating neutron stars in critical rigid rotation. We treat the differential equations…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Vassilis S. Geroyannis , Vasileios G. Karageorgopoulos

General relativistic spectra from accretion disks around rotating neutron stars in the appropriate space-time geometry for several different equation of state, spin rates and mass of the compact object have been computed. The analysis…

Astrophysics · Physics 2009-10-31 S. Bhattacharyya , R. Misra , A. V. Thampan

We present a quantum-kinetic scheme for the calculation of non-equilibrium transport properties in nanoscale systems. The approach is based on a Liouville-master equation for a reduced density operator and represents a generalization of the…

Materials Science · Physics 2009-11-10 Ralph Gebauer , Roberto Car

Consider the following nonlinear Neumann problem \[ \begin{cases} \text{div}\left(y^{a}\nabla u(x,y)\right)=0, & \text{for }(x,y)\in\mathbb{R}_{+}^{n+1}\\ \lim_{y\rightarrow0+}y^{a}\frac{\partial u}{\partial y}=-f(u), & \text{on…

Analysis of PDEs · Mathematics 2016-02-19 Changlin Xiang

We study the problem of passive imaging through convolutive channels. A scene is illuminated with an unknown, unstructured source, and the measured response is the convolution of this source with multiple channel responses, each of which is…

Information Theory · Computer Science 2017-08-25 Kiryung Lee , Felix Krahmer , Justin Romberg

Quantum trajectories are used to study OPERA findings regarding superluminal neutrinos. As the applicable stationary quantum Klein-Gordon equation is real, real quantum reduced actions and subsequent real quantum trajectories follow. The…

General Physics · Physics 2016-11-25 Edward R. Floyd

We present a lensless, Fourier-transform ghost imaging scheme by exploring the fourth-order correlation function of spatially incoherent thermal neutron waves. This technique is established on the Fermi-Dirac statistics and the…

Quantum Physics · Physics 2024-03-08 Kun Chen , Shensheng Han

Radiation transport codes are often used in astrophysics to construct spectral models. In this work we demonstrate how producing these models for a time series of data can provide unique information about supernovae (SNe). Unlike previous…

High Energy Astrophysical Phenomena · Physics 2020-02-05 Chris Ashall , Paolo Mazzali

We study the multi-dimensional properties of neutrino transfer inside supernova cores by solving the Boltzmann equations for neutrino distribution functions in genuinely six dimensional (6D) phase space. Adopting representative snapshots of…

High Energy Astrophysical Phenomena · Physics 2014-12-30 K. Sumiyoshi , T. Takiwaki , H. Matsufuru , S. Yamada

This PhD thesis is the conclusion of some of my works carried out at the Centre de Physique Th\'eorique, under the supervision of Serge Lazzarini. Two subjects are presented in the manuscript, both aiming at studying the effect of the spin…

General Relativity and Quantum Cosmology · Physics 2021-04-01 Loïc Marsot

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

Implementing Poincar\'e's `geometric conventionalism' a scalar Lorentz-covariant gravity model is obtained based on gravitationally modified Lorentz transformations (or GMLT). The modification essentially consists of an appropriate…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Jan Broekaert

Neutrino quantum kinetics is a rapidly evolving field in computational astrophysics, with a primary focus on collective neutrino oscillations in core-collapse supernovae and post-merger phases of binary neutron star mergers. In recent…

High Energy Astrophysical Phenomena · Physics 2025-01-30 Hiroki Nagakura , Masamichi Zaizen , Jiabao Liu , Lucas Johns

We propose an idea of the constrained Feynman amplitude for the scattering of the charged lepton and the virtual W-boson, $l_{\beta} + W_{\rho} \rightarrow l_{\alpha} + W_{\lambda}$, from which the conventional Pontecorvo oscillation…

High Energy Physics - Phenomenology · Physics 2020-09-18 Kazuo Fujikawa