scholarly journals De Sitter solutions in models with the Gauss-Bonnet term

2021 ◽  
Author(s):  
Sergey Vernov ◽  
Ekaterina Pozdeeva
Keyword(s):  
De Sitter ◽  
Bonnet Term

scholarly journals Stability analysis of de Sitter solutions in models with the Gauss-Bonnet term

2019 ◽  
Vol 100 (8) ◽  
Author(s):  
Ekaterina O. Pozdeeva ◽  
Mohammad Sami ◽  
Alexey V. Toporensky ◽  
Sergey Yu. Vernov
Keyword(s):  
Stability Analysis ◽  
De Sitter ◽  
Bonnet Term

A DYNAMICAL SYSTEM APPROACH TO THE GBIG COSMOLOGY

2011 ◽  
Vol 08 (06) ◽  
pp. 1179-1188 ◽  
Author(s):  
KOUROSH NOZARI ◽  
F. KIANI
Keyword(s):  
Dynamical System ◽  
Phase Space ◽  
Cosmological Constant ◽  
System Approach ◽  
Stable Solution ◽  
Late Time ◽  
Curvature Effect ◽  
De Sitter ◽  
Dynamical System Approach ◽  
Bonnet Term

We study the phase space of an extension of the normal DGP cosmology with a cosmological constant on the brane and curvature effect that is incorporated via the Gauss–Bonnet term in the bulk action. We study late-time cosmological dynamics of this scenario within a dynamical system approach. We show that the stable solution of the cosmological dynamics in this model is a de Sitter phase.

Effects of Gauss–Bonnet entropy on thermodynamics of Kiselev black hole

2020 ◽  
Vol 29 (15) ◽  
pp. 2050101
Author(s):  
Abdul Jawad ◽  
Iqra Siddique ◽  
Iarley P. Lobo ◽  
Wardat us Salam
Keyword(s):  
Black Hole ◽  
Extended Phase Space ◽  
De Sitter ◽  
Extended Phase ◽  
First Law Of Thermodynamics ◽  
Coexistence Of Phases ◽  
Combined Action ◽  
The Impact ◽  
Bonnet Term ◽  
Modified Entropy

In this paper, the thermodynamics of Reissner–Nordström-anti de Sitter black hole surrounded by quintessence is studied and the impact of the Gauss–Bonnet term is measured. The modified entropy, first law of thermodynamics and corresponding Smarr relation are derived due to the combined action of the Gauss–Bonnet term and quintessence fluid. We study the so-called black hole chemistry from the analysis of the corresponding equation-of-state, conjugate potential and the critical points in the extended phase space. To study the phase transitions, we plotted [Formula: see text], [Formula: see text] and [Formula: see text] diagrams and analyzed the conditions for the coexistence of phases.

scholarly journals Condensation of a scalar field non-minimally coupled to gravity in a cosmological context

2020 ◽  
Vol 35 (32) ◽  
pp. 2050270
Author(s):  
Amir Ghalee
Keyword(s):  
Scalar Field ◽  
Energy Density ◽  
Condensed Phase ◽  
Condensed State ◽  
De Sitter ◽  
Cosmological Perturbations ◽  
Cosmological Context ◽  
Background Density ◽  
The Universe ◽  
Bonnet Term

We present a new mechanism to condense a scalar field coupled to the Gauss–Bonnet term. We propose a scenario in which the condensed state will emerge from the background energy density in the late-Universe. During the radiation and dust-dominated eras, the energy density of the scalar field, [Formula: see text], decreases at a slower rate than the background density. Eventually, [Formula: see text] dominates over the energy density of dust and the scalar field could be condensed. In the condensed phase, we have the de Sitter phase for the universe with [Formula: see text]. Moreover, we study the cosmological perturbations of the model and explore predictions of the model.

scholarly journals De Sitter Solutions in Einstein–Gauss–Bonnet Gravity

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 149
Author(s):  
Sergey Vernov ◽  
Ekaterina Pozdeeva
Keyword(s):  
Effective Potential ◽  
Nonlinear Function ◽  
Potential Method ◽  
Einstein Equations ◽  
Late Time ◽  
De Sitter ◽  
Bonnet Gravity ◽  
Energy Models ◽  
Acceleration Of The Universe ◽  
Bonnet Term

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 Universe. The Einstein–Gauss–Bonnet gravity cosmological models are actively used both as inflationary models and as dark energy models. To modify the Einstein equations one can add a nonlinear function of the Gauss–Bonnet term or a function of the scalar field multiplied on the Gauss–Bonnet term. The effective potential method essentially simplifies the search and stability analysis of de Sitter solutions, because the stable de Sitter solutions correspond to minima of the effective potential.

scholarly journals Reconstruction procedure for nonlocal Gauss-Bonnet models

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040045
Author(s):  
Emilio Elizalde ◽  
Ekaterina O. Pozdeeva ◽  
Sergey Yu. Vernov
Keyword(s):  
Model Parameters ◽  
Local Form ◽  
De Sitter ◽  
Dynamical Equations ◽  
Reconstruction Procedure ◽  
Bonnet Term

We investigate the cosmological dynamics of nonlocally corrected gravity involving a function of the inverse d’Alembertian acting on the Gauss-Bonnet term. Casting the dynamical equations in local form, we derive the reconstruction procedure. We find conditions on the model parameters that are sufficient for the existence of de Sitter solutions and obtain these solutions explicitly.

Cosmological spacetimes

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Cosmological Model ◽  
Large Scale ◽  
Cosmic Time ◽  
De Sitter ◽  
Matter Distribution ◽  
Observable Universe ◽  
Cosmological Principle ◽  
Riemannian Spacetime ◽  
The Universe ◽  
Copernican Principle

This chapter provides a few examples of representations of the universe on a large scale—a first step in constructing a cosmological model. It first discusses the Copernican principle, which is an approximation/hypothesis about the matter distribution in the observable universe. The chapter then turns to the cosmological principle—a hypothesis about the geometry of the Riemannian spacetime representing the universe, which is assumed to be foliated by 3-spaces labeled by a cosmic time t which are homogeneous and isotropic, that is, ‘maximally symmetric’. After a discussion on maximally symmetric space, this chapter considers spacetimes with homogenous and isotropic sections. Finally, this chapter discusses Milne and de Sitter spacetimes.

scholarly journals Systematics of type IIA moduli stabilisation

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Fernando Marchesano ◽  
David Prieto ◽  
Joan Quirant ◽  
Pramod Shukla
Keyword(s):  
Scalar Potential ◽  
Systematic Search ◽  
Stability Criteria ◽  
De Sitter ◽  
Large Subset

Abstract We analyse the flux-induced scalar potential for type IIA orientifolds in the presence of p-form, geometric and non-geometric fluxes. Just like in the Calabi-Yau case, the potential presents a bilinear structure, with a factorised dependence on axions and saxions. This feature allows one to perform a systematic search for vacua, which we implement for the case of geometric backgrounds. Guided by stability criteria, we consider configurations with a particular on-shell F-term pattern, and show that no de Sitter extrema are allowed for them. We classify branches of supersymmetric and non-supersymmetric vacua, and argue that the latter are perturbatively stable for a large subset of them. Our solutions reproduce and generalise previous results in the literature, obtained either from the 4d or 10d viewpoint.

scholarly journals Massive Dirac quasinormal modes in Schwarzschild–de Sitter black holes: Anomalous decay rate and fine structure

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Almendra Aragón ◽  
Ramón Bécar ◽  
P. A. González ◽  
Yerko Vásquez
Keyword(s):  
Black Holes ◽  
Fine Structure ◽  
Decay Rate ◽  
Quasinormal Modes ◽  
De Sitter
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