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An anisotropic model describing gravity--vector gauge coupling at all energy scales is presented. The starting point is the 4+1 dimensional non--projectable Ho\v{r}ava--Lifshitz gravity theory subject to a geometrical restriction.…

High Energy Physics - Theory · Physics 2023-01-23 Alvaro Restuccia , Francisco Tello-Ortiz

We propose a simple, nonlocal modification to general relativity (GR) on large scales, which provides a model of late-time cosmic acceleration in the absence of the cosmological constant and with the same number of free parameters as in…

General Relativity and Quantum Cosmology · Physics 2018-03-30 Valeri Vardanyan , Yashar Akrami , Luca Amendola , Alessandra Silvestri

The isotropy and homogeneity of the cosmic microwave background (CMB) favors "scalar driven" early Universe inflationary models. Non-scalar fields, and in particular gauge fields, are on the other hand commonplace in all high energy…

High Energy Physics - Theory · Physics 2015-06-12 A. Maleknejad , M. M. Sheikh-Jabbari , J. Soda

We present a new framework for testing the isotropy of the Universe using cosmic microwave background data, building on the nested-sampling ANICOSMO code. Uniquely, we are able to constrain the scalar, vector and tensor degrees of freedom…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-08 Daniela Saadeh , Stephen M. Feeney , Andrew Pontzen , Hiranya V. Peiris , Jason D. McEwen

We consider a cosmological model in which the two major fluid components of the Universe, dark energy and dark matter, flow with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid,…

General Relativity and Quantum Cosmology · Physics 2013-07-24 Tiberiu Harko , Francisco S. N. Lobo

A generalized model of space-time is given, taking into consideration the anisotropic structure of fields which are depended on the position and the direction (velocity).In this framework a generalized FRW-metric the Raychaudhouri and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 P. C. Stavrinos , A. P. Kouretsis , M. Stathakopoulos

In this work, we will explore the effects of F(R) theories in the classical scheme using the anisotropic Bianchi Type I cosmological model with standard matter employing a barotropic fluid with equation of state $P=\gamma \rho$. In this…

General Relativity and Quantum Cosmology · Physics 2026-04-15 J. Socorro , Juan Luis Pérez , Luis Rey Díaz-Barrón , Abraham Espinoza García , Sinuhé Pérez Payán

We illuminate the intriguing role played by spatial anisotropy in three-dimensional Luttinger semimetals featuring quadratic band touching and long-range Coulomb interactions. We observe the anisotropy to be subject to an exceptionally slow…

Strongly Correlated Electrons · Physics 2017-03-01 Igor Boettcher , Igor F. Herbut

The standard model of cosmology is based on homogeneous-isotropic solutions of Einstein's equations. These solutions are known to be gravitationally unstable to local inhomogeneous perturbations, commonly described as evolving on a…

General Relativity and Quantum Cosmology · Physics 2011-12-19 Xavier Roy , Thomas Buchert , Sante Carloni , Nathaniel Obadia

We investigate the dynamics of closed FRW universe and anisotropic Bianchi type-IX universe characterized by two scale factors in a gravity theory including a higher curvature (Gauss-Bonnet) term. The presence of the cosmological constant…

General Relativity and Quantum Cosmology · Physics 2013-04-19 Edward J. Kim , Shinsuke Kawai

In this article, we investigate the observed cosmic acceleration in the framework of a cosmological $f(R,L_m)$ model dominated by bulk viscous matter in an anisotropic background. We consider the LRS Bianchi type I metric and derive the…

General Relativity and Quantum Cosmology · Physics 2023-06-14 Raja Solanki , Bina Patel , Lakhan V. Jaybhaye , P. K. Sahoo

Extensions of Einstein's General Relativity (GR) can formally be given a GR structure in which additional geometric degrees of freedom are mapped on an effective energy-momentum tensor. The corresponding effective cosmic medium can then be…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-11 Winfried Zimdahl , Hermano Velten , William C. Algoner

In this work we studied a two dimensional ferromagnetic system using Monte Carlo simulations. Our model includes exchange and dipolar interactions, a cubic anisotropy term, and uniaxial out-of-plane and in-plane ones. According to the set…

Materials Science · Physics 2014-06-11 O. V. Billoni , S. Bustingorry , M. Barturen , J. Milano , S. A. Cannas

The gravitational baryogensis may not generate a sufficient baryon asymmetry in the standard thermal history of the Universe when we take into account the gravitino problem. Hence it has been suggested that anisotropy of the Universe can…

High Energy Physics - Phenomenology · Physics 2016-06-01 Mitsuhiro Fukushima , Shuntaro Mizuno , Kei-ichi Maeda

We show that, due to the nonlinear nature of gravity, fluctuations in spacetime curvature generate additional gravitational attraction. This fluctuation-induced extra attraction was overlooked in the conventional understanding of the…

General Relativity and Quantum Cosmology · Physics 2024-01-09 Qingdi Wang

The field equation of orthodox general relativity are written in the context of a geometry with non-vanishing torsion, the Absolute Parallelism (AP) geometry. An AP-structure, with homogeneity and isotropy, is used for cosmological…

General Relativity and Quantum Cosmology · Physics 2012-11-08 M. I. Wanas , H. A. Hassan

Within the framework of the local limit of nonlocal gravity (NLG), we investigate a class of Bianchi type I spatially homogeneous but anisotropic cosmological models. The modified field equations are presented in this case and some special…

General Relativity and Quantum Cosmology · Physics 2023-08-24 Javad Tabatabaei , Abdolali Banihashemi , Shant Baghram , Bahram Mashhoon

Simple generic extensions of isotropic Durgapal--Fuloria stars to the anisotropic domain are presented. These anisotropic solutions are obtained by guided minimal deformations over a self gravitating isotropic system. When the isotropic and…

General Relativity and Quantum Cosmology · Physics 2018-07-04 Luciano Gabbanelli , Ángel Rincón , Carlos Rubio

Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler-Randers spacetime…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-25 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

A future detection of the Stochastic Gravitational Wave Background (SGWB) with GW experiments is expected to open a new window on early universe cosmology and on the astrophysics of compact objects. In this paper we study SGWB anisotropies,…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 N. Bartolo , D. Bertacca , S. Matarrese , M. Peloso , A. Ricciardone , A. Riotto , G. Tasinato
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