scholarly journals COSMOLOGICAL MODEL OF INTERACTING TACHYON FIELD

2012 ◽  
Vol 27 (17) ◽  
pp. 1250086 ◽  
Author(s):  
V. K. SHCHIGOLEV ◽  
M. P. ROTOVA
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Cosmological Model ◽  
Energy Flow ◽  
Field Model ◽  
Scalar Fields ◽  
Tachyon Field ◽  
First Order ◽  
Different Types ◽  
Phantom Fields

In this paper we investigate a tachyon field model in cosmology, provided its interaction with the quintessence or phantom fields. The model takes into account this interaction beyond the usual approach, in which the interaction is phenomenologically described by the energy flow between the matter components. In our model, the interaction of tachyon field with a canonical scalar field is taken into account through the interaction potential in the total Lagrangian of the system, like in the case of two or more canonical scalar fields. We obtain the different types of exact solution for the model by employing the so-called "first order formalism" procedures.

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 Cosmological constant in chameleon Brans–Dicke theory

2019 ◽  
Vol 28 (01) ◽  
pp. 1950022 ◽  
Author(s):  
Yousef Bisabr
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Exact Solutions ◽  
Effective Mass ◽  
Potential Function ◽  
Power Law ◽  
Exponential Form ◽  
First Case ◽  
Different Types

We consider a generalized Brans–Dicke model in which the scalar field has a self-interacting potential function. The scalar field is also allowed to couple nonminimally with the matter part. We assume that it has a chameleon behavior in the sense that it acquires a density-dependent effective mass. We consider two different types of matter systems which couple with the chameleon, dust and vacuum. In the first case, we find a set of exact solutions when the potential has an exponential form. In the second case, we find a power-law exact solution for the scale factor. In this case, we will show that the vacuum density decays during expansion due to coupling with the chameleon.

scholarly journals The hidden scalar Lagrangians within Horndeski theory

2020 ◽  
Vol 29 (14) ◽  
pp. 2043004
Author(s):  
Gregory W. Horndeski
Keyword(s):  
Scalar Field ◽  
Generating Function ◽  
Cotangent Bundle ◽  
Tensor Field ◽  
Scalar Fields ◽  
Field Theories ◽  
Metric Tensor ◽  
Cosmological Solutions ◽  
Different Types ◽  
Vacuum Solutions

In this paper, I show that there exists a new way to obtain scalar–tensor field theories by combining a special scalar field on the cotangent bundle with a scalar field on spacetime. These two scalar fields act as a generating function for the metric tensor. When using these two scalar fields in the Horndeski Lagrangians, we discover, while seeking Friedmann–Lemaître–Robertson–Walker-type cosmological solutions, that hidden in the Horndeski Lagrangians are nondegenerate second-order scalar Lagrangians. In accordance with Ostrogradsky’s work, these hidden scalar Lagrangians lead to multiple vacuum solutions, and thereby predict the existence of the multiverse. The multiverse is comprised of numerous different types of individual universes. For example, some begin explosively, and then coast along exponentially forever at an accelerated rate, while others begin in that manner, and then stop expanding and contract.

scholarly journals Qualitative Analysis of the Dynamics of a Two-Component Chiral Cosmological Model

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 195
Author(s):  
Viktor Zhuravlev ◽  
Sergey Chervon
Keyword(s):  
Asymptotic Behavior ◽  
Cosmological Model ◽  
Qualitative Analysis ◽  
Critical Points ◽  
Scalar Fields ◽  
Two Component ◽  
Different Types ◽  
Asymptotic Dynamics

We present a qualitative analysis of chiral cosmological model (CCM) dynamics with two scalar fields in the spatially flat Friedman–Robertson–Walker Universe. The asymptotic behavior of chiral models is investigated based on the characteristics of the critical points of the selfinteraction potential and zeros of the metric components of the chiral space. The classification of critical points of CCMs is proposed. The role of zeros of the metric components of the chiral space in the asymptotic dynamics is analysed. It is shown that such zeros lead to new critical points of the corresponding dynamical systems. Examples of models with different types of zeros of metric components are represented.

scholarly journals The Casimir energy for scalar field with mixed boundary condition

2018 ◽  
Vol 15 (10) ◽  
pp. 1850172 ◽  
Author(s):  
M. A. Valuyan
Keyword(s):  
Scalar Field ◽  
Mixed Boundary ◽  
Mixed Boundary Conditions ◽  
Scalar Fields ◽  
Casimir Energy ◽  
Massless Scalar ◽  
Regularization Technique ◽  
Massive Scalar Field ◽  
Subtraction Scheme ◽  
First Order

In this study, the first-order radiative correction to the Casimir energy for massive and massless scalar fields confined with mixed boundary conditions (BCs) (Dirichlet–Neumann) between two points in [Formula: see text] theory was computed. Two issues in performing the calculations in this work are essential: to renormalize the bare parameters of the problem, a systematic method was employed, allowing all influences from the BCs to be imported in all elements of the renormalization program. This idea yields our counterterms appeared in the renormalization program to be position-dependent. Using the Box Subtraction Scheme (BSS) as a regularization technique is the other noteworthy point in the calculation. In this scheme, by subtracting the vacuum energies of two similar configurations from each other, regularizing divergent expressions and their removal process were significantly facilitated. All the obtained answers for the Casimir energy with the mixed BC were consistent with well-known physical grounds. We also compared the Casimir energy for massive scalar field confined with four types of BCs (Dirichlet, Neumann, mixed of them and Periodic) in [Formula: see text] dimensions with each other, and the sign and magnitude of their values were discussed.

scholarly journals SELF-DUAL VORTICES IN THE ABELIAN CHERN–SIMONS MODEL WITH TWO COMPLEX SCALAR FIELDS

2008 ◽  
Vol 23 (26) ◽  
pp. 2189-2198 ◽  
Author(s):  
YI-SHI DUAN ◽  
LI-DA ZHANG ◽  
YU-XIAO LIU
Keyword(s):  
Angular Momentum ◽  
Scalar Field ◽  
Field Model ◽  
Current Method ◽  
Scalar Fields ◽  
The Self ◽  
Complex Scalar ◽  
Topological Current ◽  
Chern Simons ◽  
Topological Term

Making use of ϕ-mapping topological current method, we discuss the self-dual vortices in the Abelian Chern–Simons model with two complex scalar fields. For each scalar field, an exact nontrivial equation with a topological term which is missing in many references is derived analytically. The general angular momentum is obtained. The magnetic flux which relates the two scalar fields is calculated. Furthermore, we investigate the vortex evolution processes, and find that because of the presence of the vortex molecule, these evolution processes are more complicated than the vortex evolution processes in the corresponding single scalar field model.

scholarly journals PHANTOM FIELDS: BOUNCE SOLUTIONS IN THE EARLY UNIVERSE AND S-BRANES

2008 ◽  
Vol 17 (12) ◽  
pp. 2351-2358 ◽  
Author(s):  
VLADIMIR DZHUNUSHALIEV ◽  
VLADIMIR FOLOMEEV ◽  
KAIRAT MYRZAKULOV ◽  
RATBAY MYRZAKULOV
Keyword(s):  
Cosmological Model ◽  
Field Potential ◽  
Scalar Fields ◽  
Special Choice ◽  
De Sitter ◽  
Brane Solution ◽  
Phantom Scalar ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Phantom Fields

A cosmological model with two phantom scalar fields with a special choice of the field potential is considered. The obtained regular solution describes a bounce with a subsequent transition to the de Sitter stage of the expansion of the universe. This solution could also be interpreted as an S-brane solution.

scholarly journals Smooth Crossing ofwΛ=−1Line in a Single Scalar Field Model

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
Abhik Kumar Sanyal
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Cosmological Model ◽  
Simple Form ◽  
Cold Dark Matter ◽  
Field Model ◽  
Late Time ◽  
Transient Phenomenon ◽  
Phantom Divide ◽  
Phantom Divide Line

Smooth double crossing of the phantom divide linewΛ=−1has been found possible with a single minimally coupled scalar field for the most simple form of generalizedk-essence cosmological model, in the presence of background cold dark matter. Such crossing is a sufficiently late time transient phenomenon and does not have any pathological behaviour.

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.

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