scholarly journals A general exact solution of the Einstein-Dirac equations with the cosmological constant in homogeneous space

2004 ◽  
Vol 98 (4) ◽  
pp. 619-628 ◽  
Author(s):  
V. A. Zhelnorovich
Keyword(s):  
Exact Solution ◽  
Cosmological Constant ◽  
Homogeneous Space ◽  
Dirac Equations

scholarly journals Global monopole metric in 2 + 1 dimensions

2019 ◽  
Vol 16 (01) ◽  
pp. 1950006
Author(s):  
S. Habib Mazharimousavi ◽  
M. Halilsoy
Keyword(s):  
Exact Solution ◽  
Cosmological Constant ◽  
Electric Charge ◽  
Radial Distance ◽  
Series Solutions ◽  
Global Monopole ◽  
Negative Cosmological Constant ◽  
Consistent Manner ◽  
Positive Integers

In order to obtain the geometry of a global monopole without cosmological constant and electric charge in [Formula: see text] dimensions, we make use of the broken [Formula: see text] symmetry. In the absence of an exact solution, we determine the series solutions for both the metric and monopole functions in a consistent manner that satisfies all equations in appropriate powers. The new expansion elements are of the form [Formula: see text] for the radial distance [Formula: see text] and positive integers [Formula: see text] and [Formula: see text] constrained by [Formula: see text]. To the lowest order of expansion, we find that in analogy with the negative cosmological constant the geometry of the global monopole acts repulsively, i.e. in the absence of a cosmological constant the global monopole plays at large distances the role of a negative cosmological constant.

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 Vacuum solutions of Einstein equations that depend on one coordinate

2020 ◽  
pp. 10-11
Author(s):  
S. Parnovsky
Keyword(s):  
Exact Solution ◽  
General Theory ◽  
Cosmological Constant ◽  
Gravitational Wave ◽  
Einstein Equations ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Vacuum Metrics ◽  
Vacuum Solutions ◽  
Zero Frequency

In the famous textbook written by Landau and Lifshitz all the vacuum metrics of the general theory of relativity are derived, which depend on one coordinate in the absence of a cosmological constant. Unfortunately, when considering these solutions the authors missed some of the possible solutions discussed in this article. An exact solution is demonstrated, which is absent in the book by Landau and Lifshitz. It describes space-time with a gravitational wave of zero frequency. It is shown that there are no other solutions of this type than listed above and Minkowski’s metrics. The list of vacuum metrics that depend on one coordinate is not complete without solution provided in this paper.

An exact solution of the Einstein-Dirac equations

1983 ◽  
Vol 16 (2) ◽  
pp. 317-320 ◽  
Author(s):  
C J Radford ◽  
A H Klotz
Keyword(s):  
Exact Solution ◽  
Dirac Equations

scholarly journals EXACT SOLUTION FOR THE MASSLESS CYLINDRICALLY SYMMETRIC SCALAR FIELD IN GENERAL RELATIVITY, WITH COSMOLOGICAL CONSTANT

2009 ◽  
Vol 24 (31) ◽  
pp. 5991-6000 ◽  
Author(s):  
D. MOMENI ◽  
H. MIRAGHAEI
Keyword(s):  
Exact Solution ◽  
General Relativity ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Cylindrical Symmetry ◽  
Cosmological Models ◽  
Cyclic Universe ◽  
Cylindrically Symmetric

In this paper, we present a new exact solution for scalar field with cosmological constant in cylindrical symmetry. Associated cosmological models, including a model that describes a cyclic universe, are discussed.

scholarly journals FIVE-DIMENSIONAL VACUUM EINSTEIN SPACETIMES IN C-METRIC LIKE COORDINATES

2010 ◽  
Vol 25 (32) ◽  
pp. 2727-2743 ◽  
Author(s):  
WEI XU ◽  
LIU ZHAO ◽  
BIN ZHU
Keyword(s):  
Exact Solution ◽  
Cosmological Constant ◽  
Coordinate System ◽  
Standard Form ◽  
Liouville Theory ◽  
De Sitter ◽  
Close Analogy ◽  
Causal Structures ◽  
Kaluza Klein

A five-dimensional Einstein spacetime with (non)vanishing cosmological constant is analyzed in detail. The metric is in close analogy with the four-dimensional massless uncharged C-metric in many aspects. The coordinate system, horizons and causal structures, relations to standard form of de Sitter, anti de Sitter and Minkowski vacua are investigated. After a boost and Kaluza–Klein reduction, we get an exact solution of four-dimensional Einstein–Maxwell–Liouville theory which reduces to a solution to Einstein–Liouville theory in the limit of zero boost velocity and to that of Einstein–Maxwell–dilaton theory in the case of zero cosmological constant.

New exact solution to the Einstein-Dirac equations

1979 ◽  
Vol 19 (6) ◽  
pp. 1635-1640 ◽  
Author(s):  
Kay R. Pechenick ◽  
Jeffrey M. Cohen
Keyword(s):  
Exact Solution ◽  
Dirac Equations
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