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We consider static cosmological solutions along with their stability properties in the framework of a recently proposed theory of massive gravity. We show that the modifcation introduced in the cosmological equations leads to several new…

General Relativity and Quantum Cosmology · Physics 2012-07-27 Luca Parisi , Ninfa Radicella , Gaetano Vilasi

We investigate a bounce realization in the framework of higher order curvature in $ f(R,T) $ modified theory of gravity. We perform a detailed analysis of the cosmological parameters to explain the contraction phase, the bounce phase, and…

General Relativity and Quantum Cosmology · Physics 2023-07-19 J. K. Singh , Shaily , Akanksha Singh , Aroonkumar Beesham , Hamid Shabani

In this paper we provide approximate analytical analysis of stability of nonsingular inflationary chaotic-type cosmological models. Initial conditions for nonsingular solutions at the bounce correspond to dominance of potential part of the…

Astrophysics · Physics 2009-11-10 G. V. Vereshchagin

In this paper, we have studied the bouncing behavior of the cosmological models formulated at the background of the Hubble function in the F(R, G) theory of gravity, where R and G denote the Ricci scalar and Gauss-Bonnet invariant. The…

General Relativity and Quantum Cosmology · Physics 2022-12-02 Santosh V Lohakare , Francisco Tello-Ortiz , S. K. Tripathy , B. Mishra

This manuscript is based on an investigation of bouncing cosmology in a 4D Einstein Gauss-Bonnet gravity. Various bouncing models such as symmetric bounce, matter bounce, super bounce, and oscillatory bounce have been examined. Expressions…

General Relativity and Quantum Cosmology · Physics 2023-06-16 M. Zubair , Mushayydha Farooq

We explore dynamics of cosmological models with bounce solutions evolving on a spatially flat Friedmann-Lemaitre-Robertson-Walker background. We consider cosmological models that contain the Hilbert-Einstein curvature term, the induced…

General Relativity and Quantum Cosmology · Physics 2016-12-08 Ekaterina O. Pozdeeva , Maria A. Skugoreva , Alexey V. Toporensky , Sergey Yu. Vernov

We investigate the cosmology of a class of model with noncanonical scalar field and matter both in FRW closed and open background. Writing the Einstein Equations in terms of dimensionless dynamical variables suitable for studying bouncing…

General Relativity and Quantum Cosmology · Physics 2015-01-12 Manabendra Sharma

Motivated by the conjecture that the cosmological constant problem could be solved by strong quantum effects in the infrared we use the exact flow equation of Quantum Einstein Gravity to determine the renormalization group behavior of a…

High Energy Physics - Theory · Physics 2009-11-07 M. Reuter , F. Saueressig

We study stability of singularity-free cosmological solutions with positive cosmological constant based on projectable Ho\v{r}ava-Lifshitz (HL) theory. In HL theory, the isotropic and homogeneous cosmological solutions with bounce can be…

General Relativity and Quantum Cosmology · Physics 2017-03-08 Yosuke Misonoh , Mitsuhiro Fukushima , Shoichiro Miyashita

We study the behavior of a general gravitational action, including quadratic terms in the curvature, supplemented by a compact scalar field in 4+1 dimensions. The generalized Einstein equation for this system admits solutions which are…

High Energy Physics - Theory · Physics 2009-10-31 Hael Collins , Bob Holdom

In this paper, in an FLRW background and a perfect fluid equation of state, we explore the possibility of the realization of an emergent scenario in a 4D regularized extension of Einstein-Gauss-Bonnet gravity, with the field equations…

General Relativity and Quantum Cosmology · Physics 2024-06-12 Mrinnoy M. Gohain , Kalyan Bhuyan

The stability under radial and vertical perturbations of circular orbits associated to particles orbiting a spherically symmetric center of attraction is study in the context of the n-dimensional: Newtonian theory of gravitation, Einstein's…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Valeria M. Rosa , Patricio S. Letelier

We explicitly confirm that spatially flat non-singular bouncing cosmologies make sense as effective theories. The presence of a non-singular bounce in a spatially flat universe implies a temporary violation of the null energy condition,…

High Energy Physics - Theory · Physics 2016-05-11 Michael Koehn , Jean-Luc Lehners , Burt Ovrut

Despite many nice properties and numerous achievements, general relativity is not a complete theory. One of actual approaches towards more complete theory of gravity is its nonlocal modification. We present here a brief review of nonlocal…

General Relativity and Quantum Cosmology · Physics 2017-01-04 Branko Dragovich

We explore simple but novel bouncing solutions of general relativity that avoid singularities. These solutions require curvature k=+1, and are supported by a negative cosmological term and matter with -1 < w < -1/3. In the case of moderate…

High Energy Physics - Theory · Physics 2014-01-16 Peter W. Graham , Bart Horn , Shamit Kachru , Surjeet Rajendran , Gonzalo Torroba

We investigate the realization of a nonsingular cosmological bounce in metric $f(R)$ gravity using a controlled exponential deformation of the Starobinsky $R^{2}$ model. Adopting a smooth Gaussian-type bouncing scale factor, we first…

General Relativity and Quantum Cosmology · Physics 2026-03-31 G. G. L. Nashed , A. Eid

This paper analyzes the stability of the closed Einstein static universe by using linear homogeneous perturbations in the framework of energy-momentum squared gravity. This newly developed proposal resolves the primordial singularity and…

General Relativity and Quantum Cosmology · Physics 2021-08-25 M. Sharif , M. Zeeshan Gul

De Sitter solutions play an important role in cosmology because the knowledge of unstable de Sitter solutions can be useful to describe inflation, whereas stable de Sitter solutions are often used in models of late-time acceleration of the…

General Relativity and Quantum Cosmology · Physics 2021-05-18 Sergey Vernov , Ekaterina Pozdeeva

We address the stability issue of Ricci-flat and maximally symmetric spacetimes in nonlocal gravity to all perturbative orders in the gravitational perturbation. Assuming a potential at least cubic in curvature tensors but quadratic in the…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Fabio Briscese , Gianluca Calcagni , Leonardo Modesto

We consider general curvature-invariant modifications of the Einstein-Hilbert action that become important only in regions of extremely low space-time curvature. We investigate the far future evolution of the universe in such models,…