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Screened modified gravity (SMG) is a kind of scalar-tensor theories with screening mechanisms, which can generate screening effect to suppress the fifth force in high density environments and pass the solar system tests. Meanwhile, the…

General Relativity and Quantum Cosmology · Physics 2016-06-14 Xing Zhang , Wen Zhao , He Huang , Yifu Cai

Chern-Simons modified gravity is a string-theory and loop-quantum-gravity inspired effective theory that modifies General Relativity by adding a parity-violating Pontryagin density to the Einstein-Hilbert action multiplied by a coupling…

General Relativity and Quantum Cosmology · Physics 2010-04-15 Nicolas Yunes , David N. Spergel

A three-dimensional (3D) Poisson solver with longitudinal periodic and transverse open boundary conditions can have important applications in beam physics of particle accelerators. In this paper, we present a fast efficient method to solve…

Accelerator Physics · Physics 2017-09-13 Ji Qiang

We describe the numerical code N-MODY, a parallel particle-mesh code for collisionless N-body simulations in modified Newtonian dynamics (MOND). N-MODY is based on a numerical potential solver in spherical coordinates that solves the…

Astrophysics · Physics 2008-04-01 Pasquale Londrillo , Carlo Nipoti

We present a new high-order accurate spectral element solution to the two-dimensional scalar Poisson equation subject to a general Robin boundary condition. The solution is based on a simplified version of the shifted boundary method…

Numerical Analysis · Mathematics 2023-10-27 Jens Visbech , Allan Peter Engsig-Karup , Mario Ricchiuto

The nonlinear Klein-Gordon (NLKG) equation on a manifold $M$ in the nonrelativistic limit, namely as the speed of light $c$ tends to infinity, is considered. In particular, a higher-order normalized approximation of NLKG (which corresponds…

Analysis of PDEs · Mathematics 2018-10-15 Stefano Pasquali

We derive the Klein--Gordon equation for a single scalar field coupled to gravity at second order in perturbation theory and leading order in slow-roll. This is done in two ways: we derive the Klein--Gordon equation first using the Einstein…

Astrophysics · Physics 2009-06-23 Karim A. Malik , David Seery , Kishore N. Ananda

We give an algorithm that reduces the straight skeleton to the motorcycle graph in $O(n\log n)$ time for simple polygons and $O(n(\log n)\log m)$ time for a planar straight line graph (PSLG) with $m$ connected components. This improves on…

Computational Geometry · Computer Science 2014-08-07 John C. Bowers

Astrophysical data analysis of the weak-field predictions support the claim that modified gravity (MOG) theories provide a self-consistent, scale-invariant, universal description of galaxy rotation curves, without the need of non-baryonic…

Astrophysics of Galaxies · Physics 2009-08-09 J. R. Brownstein

This study employs the effective field theory approach to quantum gravity to investigate a non-Abelian gauge theory involving scalar particles coupled to gravity. The study demonstrates explicitly that the Slavnov-Taylor identities are…

High Energy Physics - Theory · Physics 2023-06-14 Huan Souza , L. Ibiapina Bevilaqua , A. C. Lehum

Simulations at physical quark masses are affected by the critical slowing down of the solvers. Multigrid preconditioning has proved to deal effectively with this problem. Multigrid accelerated simulations at the physical value of the pion…

High Energy Physics - Lattice · Physics 2018-04-18 Simone Bacchio , Constantia Alexandrou , Jacob Finkerath

Modified Gravity theories generally affect the Poisson equation and the gravitational slip (effective anisotropic stress) in an observable way, that can be parameterized by two generic functions ($\eta$ and $\mu$) of time and space. We bin…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-06 Santiago Casas , Martin Kunz , Matteo Martinelli , Valeria Pettorino

In massive gravity, galileon, and braneworld explanations of cosmic acceleration, force modifications are screened by nonlinear derivative self-interactions of the scalar field mediating that force. Interactions between the field of a…

High Energy Physics - Theory · Physics 2013-04-03 Takashi Hiramatsu , Wayne Hu , Kazuya Koyama , Fabian Schmidt

In self-consistent N-body simulations of collisionless systems, gravitational interactions are modified on small scales to remove singularities and simplify the task of numerically integrating the equations of motion. This `gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Joshua E. Barnes

We establish improved uniform error bounds on time-splitting methods for the long-time dynamics of the nonlinear Klein--Gordon equation (NKGE) with weak cubic nonlinearity, whose strength is characterized by $\varepsilon^2$ with $0 <…

Numerical Analysis · Mathematics 2021-10-01 Weizhu Bao , Yongyong Cai , Yue Feng

Current acceleration of the cosmic expansion leads to coincidence as well as fine-tuning issues in the framework of general relativity. Dynamical scalar fields have been introduced in response of these problems, some of them invoking…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-25 Sandrine Schlogel , Sebastien Clesse , Andre Fuzfa

We present $N$-body cosmlogical simulations in the framework of the Newtonian limit of scalar-tensor theories of gravity. The scalar field is described by a modified Helmholtz equation with a source that is coupled to the standard Poisson…

Astrophysics · Physics 2009-06-23 M. A. Rodriguez-Meza

The interplay between quantum theory and general relativity remains one of the main challenges of modern physics. A renewed interest in the low-energy limit is driven by the prospect of new experiments that could probe this interface. Here…

General Relativity and Quantum Cosmology · Physics 2024-11-18 Jelle Hartong , Emil Have , Niels A. Obers , Igor Pikovski

Recently there has been renewed interest in signed distance bound representations due to their unique properties for 3D shape modelling. This is especially the case for deep learning-based bounds. However, it is beneficial to work with…

Graphics · Computer Science 2024-04-08 Nenad Markuš , Mirko Sužnjević

In order to approach the pion--multinucleon problem, we have found it convenient to reformulate the general N--body theory starting from the fully unclusterized (i.e., N <- N) amplitude. If we rewrite such an amplitude in terms of new…

Nuclear Theory · Physics 2009-10-28 G. Cattapan , L. Canton
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