scholarly journals Critical Combinations of Higher-Order Terms in Einstein-Maxwell Theory and Compactification

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Nahomi Kan ◽  
Kiyoshi Shiraishi
Keyword(s):  
Higher Order ◽  
De Sitter ◽  
Spontaneous Compactification ◽  
Maxwell Theory ◽  
Higher Derivative ◽  
Higher Dimensional ◽  
Inflationary Phase ◽  
Expansion Time ◽  
Higher Order Terms

We discuss the role of a particular combination of higher derivative terms in higher dimensional theories, particularly in the background of spontaneous compactification. Two classes of theories are proposed in this paper. The first model as a generalization of the critical gravity with the Maxwell field could have a de Sitter solution. We consider the Lanczos-Lovelock term and Horndeski term as well as the higher-order Maxwell term for the second model, which contains a possible longer expansion time for the inflationary phase. It is interesting that both models can be regarded as the generalization of the Randjbar-Daemi, Salam and Strathdee (RSS) model and give the well behavior for inflation stage under the specific assumptions.

scholarly journals Regular Solutions in Higher-Derivative Gravity

Universe ◽  
2018 ◽  
Vol 4 (12) ◽  
pp. 140 ◽  
Author(s):  
Breno Giacchini ◽  
Tibério Netto
Keyword(s):  
Higher Order ◽  
Newtonian Potential ◽  
Regular Solutions ◽  
Quantum Properties ◽  
Higher Derivative ◽  
Gravitational Theories ◽  
Higher Order Terms

Local gravitational theories with more than four derivatives can have remarkable quantum properties. Namely, they can be super-renormalizable and may be unitary in the Lee-Wick sense, if the massive poles of the propagator are complex. It is important, therefore, to also explore the classical aspects of these theories. In this talk we present recent results in this direction. Specifically, we discuss the effect that that higher-order terms can have on the Newtonian potential and related singularities.

scholarly journals Role of Higher-Order Terms in Local Piston Theory

2019 ◽  
Vol 56 (1) ◽  
pp. 388-391 ◽  
Author(s):  
Marius-Corné Meijer ◽  
Laurent Dala
Keyword(s):  
Higher Order ◽  
Piston Theory ◽  
Higher Order Terms

On the evolution and stability of cosmological perturbations in higher order scalar–tensor theories of gravity

2019 ◽  
Vol 97 (4) ◽  
pp. 360-373
Author(s):  
Fateme Rajabi ◽  
Kourosh Nozari
Keyword(s):  
Scalar Field ◽  
Higher Order ◽  
De Sitter ◽  
Cosmological Perturbations ◽  
First Order ◽  
Higher Order Terms ◽  
General Scalar ◽  
New Type ◽  
Theories Of Gravity ◽  
The Stability

We study a new type of extended theory of gravity in the framework of general scalar–tensor theories in which the higher order terms of curvature are coupled with a scalar field and its derivatives. We analyze the stability and evolution of cosmological perturbations in this setup. For this purpose, we perturb the Hubble parameter, matter density, and scalar field to check stability and evolution of perturbations to first order. In this framework, we investigate stability conditions for de Sitter and power law solutions and we examine viability of cosmological evolution of these perturbations. We consider some specific f(R) models and show that the stability analysis gives some constraints on the parameters of these models.

Lovelock black holes in the presence of nonlinear electrodynamics

2015 ◽  
Vol 24 (06) ◽  
pp. 1550040 ◽  
Author(s):  
Seyed Hossein Hendi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Nonlinear Electrodynamics ◽  
Thermodynamic Quantities ◽  
De Sitter ◽  
Maxwell Theory ◽  
Hole Radius ◽  
Higher Dimensional ◽  
Effective Cosmological Constant ◽  
Black Hole Solutions

In this paper, we consider third-order Lovelock–Maxwell gravity with additional (Fμν Fμν)2 term as a nonlinearity correction of the Maxwell theory. We obtain black hole solutions with various horizon topologies (and various number of horizons) in which their asymptotical behavior can be flat or anti-de Sitter with an effective cosmological constant. We investigate the effects of Lovelock and electrodynamic corrections on properties of the solutions. Then, we restrict ourselves to asymptotically flat solutions and calculate the conserved and thermodynamic quantities. We check the first law of thermodynamics for these black hole solutions and calculate the heat capacity to analyze stability. Although higher dimensional black holes in Einstein gravity are unstable, here we look for suitable constraints on the black hole radius to find thermally stable black hole solutions.

scholarly journals Exact solutions to Einstein–Maxwell theory on Eguchi–Hanson space

2017 ◽  
Vol 32 (17) ◽  
pp. 1750098 ◽  
Author(s):  
A. M. Ghezelbash ◽  
V. Kumar
Keyword(s):  
Cosmological Constant ◽  
Exact Solutions ◽  
De Sitter Space ◽  
Space Time ◽  
De Sitter ◽  
Maxwell Theory ◽  
Analytical Functions ◽  
Higher Dimensional ◽  
All Solutions ◽  
Metric Functions

In this paper, we construct explicit analytical exact solutions to the six and higher-dimensional Einstein–Maxwell theory. In all solutions, a subspace of the metric is the Eguchi–Hanson space where the metric functions are completely determined in terms of known analytical functions. Moreover, we find the solutions can be extended from nonstationary exact solutions to Einstein–Maxwell theory with cosmological constant. We show that the solutions are asymptotically expanding patches of de Sitter space–time.

Correction: Role of Higher-Order Terms in Local Piston Theory

2020 ◽  
Vol 57 (5) ◽  
pp. 1001-1001
Author(s):  
Marius-Corné Meijer ◽  
Laurent Dala
Keyword(s):  
Higher Order ◽  
Piston Theory ◽  
Higher Order Terms

scholarly journals EASY HOLOGRAPHY

2013 ◽  
Vol 22 (12) ◽  
pp. 1342013
Author(s):  
HEIKKI ARPONEN
Keyword(s):  
Homogeneous Spaces ◽  
Three Dimensional ◽  
De Sitter ◽  
Asymptotic Symmetry ◽  
Infinite Dimensional ◽  
Higher Dimensional ◽  
Black Hole Information ◽  
Holographic Description ◽  
Area Law

It is argued that the role of infinite-dimensional asymptotic symmetry groups in gravity theories are essential for a holographic description of gravity and possibly to a resolution of the black hole information paradox. I present a simple toy model in two-dimensional hyperbolic/anti-de Sitter (AdS) space and describe, by very elementary considerations, how the asymptotic symmetry group is responsible for the entropy area law. Similar results apply also in three-dimensional AdS space. The failure of the approach in higher-dimensional AdS spaces is explained and resolved by considering other asymptotically noncompact homogeneous spaces.

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