scholarly journals New Anisotropic Exact Solution in Multifield Cosmology

Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 323 ◽  
Author(s):  
Andronikos Paliathanasis
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Chiral Model ◽  
Stability Conditions ◽  
Field Equations ◽  
Background Space ◽  
Scalar Field Cosmology ◽  
The Stability

In the case of two-scalar field cosmology, and specifically for the Chiral model, we determine an exact solution for the field equations with an anisotropic background space. The exact solution can describe anisotropic inflation with a Kantowski–Sachs geometry and can be seen as the anisotropic analogue of the hyperbolic inflation. Finally, we investigate the stability conditions for the exact solution.

scholarly journals Cosmological solutions in Hořava-Lifshitz scalar field theory

2020 ◽  
Vol 75 (6) ◽  
pp. 523-532 ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Genly Leon
Keyword(s):  
Scalar Field ◽  
Singularity Analysis ◽  
Exponential Potential ◽  
Field Equations ◽  
Explicit Integration ◽  
Gravitational Field Equations ◽  
Background Space ◽  
Painlevé Property ◽  
Cosmological Solutions ◽  
Scalar Field Cosmology

AbstractWe perform a detailed study of the integrability of the Hořava-Lifshitz scalar field cosmology in a Friedmann-Lemaître-Robertson-Walker background space-time. The approach we follow to determine the integrability is that of singularity analysis. More specifically, we test whether the gravitational field equations possess the Painlevé property. For the exponential potential of the scalar field, we are able to perform an analytic explicit integration of the field equations and write the solution in terms of a Laurent expansion and more specifically write the solution in terms of right Painlevé series.

scholarly journals Scalar field cosmology in Lyra's geometry

2015 ◽  
Vol 3 (2) ◽  
pp. 117 ◽  
Author(s):  
V. K. Shchigolev ◽  
E. A. Semenova
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Generating Function ◽  
Function Method ◽  
Scalar Fields ◽  
First Order ◽  
Homogeneous Cosmological Models ◽  
Different Types ◽  
Lyra’S Geometry ◽  
Scalar Field Cosmology

<p>The new classes of homogeneous cosmological models for the scalar fields are build in the context of Lyra’s geometry. The different types of exact solution for the model are obtained by applying two procedures, viz the generating function method and the first order formalism.</p>

scholarly journals Integrability and cosmological solutions in Einstein-æther-Weyl theory

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Genly Leon
Keyword(s):  
Scalar Field ◽  
Cosmological Model ◽  
Conservation Law ◽  
Analytic Solutions ◽  
Special Interests ◽  
Field Equations ◽  
Background Space ◽  
Weyl Theory ◽  
Cosmological Solutions

AbstractWe consider a Lorentz violating scalar field cosmological model given by the modified Einstein-æther theory defined in Weyl integrable geometry. The existence of exact and analytic solutions is investigated for the case of a spatially flat Friedmann–Lemaître–Robertson–Walker background space. We show that the theory admits cosmological solutions of special interests. In addition, we prove that the cosmological field equations admit the Lewis invariant as a second conservation law, which indicates the integrability of the field equations.

scholarly journals Anisotropic power-law inflation in a two-scalar-field model with a mixed kinetic term

2017 ◽  
Vol 26 (07) ◽  
pp. 1750072 ◽  
Author(s):  
Tuan Q. Do ◽  
Sonnet Hung Q. Nguyen
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Field Model ◽  
Scalar Fields ◽  
Kinetic Term ◽  
Type I ◽  
Field Equations ◽  
Scalar Field Model ◽  
Phantom Scalar ◽  
The Stability

We examine whether an extended scenario of a two-scalar-field model, in which a mixed kinetic term of canonical and phantom scalar fields is involved, admits the Bianchi type I metric, which is homogeneous but anisotropic spacetime, as its power-law solutions. Then, we analyze the stability of the anisotropic power-law solutions to see whether these solutions respect the cosmic no-hair conjecture or not during the inflationary phase. In addition, we will also investigate a special scenario, where the pure kinetic terms of canonical and phantom fields disappear altogether in field equations, to test again the validity of cosmic no-hair conjecture. As a result, the cosmic no-hair conjecture always holds in both these scenarios due to the instability of the corresponding anisotropic inflationary solutions.

scholarly journals Noether symmetries of Einstein-aether scalar field cosmology

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Yusuf Kucukakca ◽  
Amin Rezaei Akbarieh
Keyword(s):  
Scalar Field ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Noether Symmetries ◽  
Field Equations ◽  
Symmetry Approach ◽  
Expansion Of The Universe ◽  
Frw Metric ◽  
Scalar Field Cosmology ◽  
The Universe

AbstractIn this paper, we explore an Einstein-aether cosmological model by adding the scalar field in which it has an interaction with the aether field. For the cosmological implications of the model, we consider that the universe can be described by the spatially flat FRW metric together with the matter dominated universe. Applying Noether symmetry approach to the point-like Lagrangian we determine the explicit forms of unknown functions i.e. the potential and coupling function. We solve the analytical cosmological solutions of the field equations admitting the Noether symmetry, basically divided into two parts. Our results show that the obtained solutions lead to an accelerated expansion of the universe. We also discuss the tensor perturbations within the framework of this model in order to get information about the mass of gravitational waves.

scholarly journals Exact Kantowski–Sachs spacetimes in Einstein–Aether scalar field theory

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Genly Leon ◽  
Andronikos Paliathanasis ◽  
N. Dimakis
Keyword(s):  
Field Theory ◽  
Scalar Field ◽  
Functional Form ◽  
Analytic Solution ◽  
Analytic Solutions ◽  
Field Equations ◽  
Scalar Field Theory ◽  
Gravitational Field Equations ◽  
Background Space ◽  
Gravitational Model

AbstractExact and analytic solutions in Einstein–Aether scalar field theory with Kantowski–Sachs background space are determined. The theory of point symmetries is applied to determine the functional form of the unknown functions which defines the gravitational model. Conservation laws are applied to reduce the order of the field equations and write the analytic solution. Moreover, in order to understand the physical behaviour of the cosmological model a detailed analysis of the asymptotic behaviour for solutions of the gravitational field equations is performed.

scholarly journals BOUNCING UNIVERSE WITH THE NON-MINIMALLY COUPLED SCALAR FIELD AND ITS RECONSTRUCTION

2009 ◽  
Vol 24 (29) ◽  
pp. 2363-2376 ◽  
Author(s):  
J. SADEGHI ◽  
F. MILANI ◽  
A. R. AMANI
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
State Parameter ◽  
Stability Conditions ◽  
Bouncing Universe ◽  
Equation Of State Parameter ◽  
The Stability

In this paper we consider a non-minimally coupled scalar field, and show that its equation of state parameter can cross over -1, ω→-1, and bouncing condition. Also we obtain the stability conditions and consider reconstructing for our model.

Sign in / Sign up

Export Citation Format

Share Document