Exact solutions in string-motivated scalar-field cosmology

1992 ◽  
Vol 45 (4) ◽  
pp. R997-R999 ◽  
Author(s):  
Murat Özer ◽  
M. O. Taha
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Scalar Field Cosmology

scholarly journals Nonlinear Schrödinger-type formulation of scalar field cosmology: Two barotropic fluids and exact solutions

2020 ◽  
Vol 35 (19) ◽  
pp. 2050157
Author(s):  
Chonticha Kritpetch ◽  
Jarunee Sanongkhun ◽  
Pichet Vanichchapongjaroen ◽  
Burin Gumjudpai
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Time Dependent ◽  
Frw Cosmology ◽  
Dependent Case ◽  
Nonlinear Schrödinger ◽  
Barotropic Fluids ◽  
Scalar Field Cosmology ◽  
Formulation Variables ◽  
Canonical Scalar Field

Time-independent nonlinear Schrödinger-type (NLS) formulation of FRW cosmology with canonical scalar field is considered in the case of two barotropic fluids. We derived Friedmann formulation variables in terms of NLS variables. Seven exact solutions found by D’Ambroise [Ph.D. thesis, arXiv:1005.1410 ] and one new found solution are explored and tested in cosmology. The result suggests that time-independent NLS formulation of cosmology case should be upgraded to the time-dependent case.

A new look at the Schrödinger equation in exact scalar field cosmology

2019 ◽  
Vol 16 (02) ◽  
pp. 1950022 ◽  
Author(s):  
I. V. Fomin ◽  
S. V. Chervon ◽  
S. D. Maharaj
Keyword(s):  
Wave Function ◽  
Scalar Field ◽  
Exact Solutions ◽  
Closed Form ◽  
Generating Function ◽  
Hubble Parameter ◽  
Scalar Potential ◽  
Scale Factor ◽  
Simple Transformation ◽  
Scalar Field Cosmology

We propose a new representation of the Schrödinger-like equation for scalar field Friedmann cosmology where the scalar field is the argument, and the Hubble parameter is the analogue to the wave function. Such an approach gives us the possibility to use the Schrödinger potential as a generating function which leads to generalization of known exact solutions. Further, we find a simple transformation of the Hubble parameter which generates new solutions from the Schrödinger-like equation. Several examples are identified where exact forms for the scale factor, Hubble parameter and scalar potential can be written in closed form. Earlier results are regained in our approach.

The dynamical system approach to scalar field cosmology

2000 ◽  
Vol 17 (8) ◽  
pp. 1783-1814 ◽  
Author(s):  
E Gunzig ◽  
V Faraoni ◽  
A Figueiredo ◽  
T M Rocha Filho ◽  
L Brenig
Keyword(s):  
Dynamical System ◽  
Scalar Field ◽  
System Approach ◽  
Dynamical System Approach ◽  
Scalar Field Cosmology

scholarly journals Noncommutativity and scalar field cosmology

2007 ◽  
Vol 76 (8) ◽  
Author(s):  
W. Guzmán ◽  
M. Sabido ◽  
J. Socorro
Keyword(s):  
Scalar Field ◽  
Scalar Field Cosmology

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.

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