ALGEBRAIC PROGRAMMING IN THE HAMILTONIAN TREATMENT OF AN INFLATIONARY MODEL

1995 ◽  
Vol 06 (03) ◽  
pp. 317-326 ◽  
Author(s):  
DUMITRU N. VULCANOV
Keyword(s):  
Scalar Field ◽  
Hamiltonian Formulation ◽  
Space Time ◽  
Dynamic Equations ◽  
Inflationary Model ◽  
Action Functional ◽  
Algebraic Programming ◽  
Initial Space ◽  
New Procedures ◽  
Inflationary Models

This article presents new procedures in REDUCE language using the EXCALC package (adapted for IBM-PC machines) for algebraic programming in the Hamiltonian formulation of inflationary models based on a scalar field non-minimally coupled with gravity. The (3+1)-dimensional split of the action functional of the model and the constraint and dynamic equations are obtained. These equations are transposed in computer procedures. The results obtained after processing some examples of initial space-time models are presented here.

ADM FORMALISM APPLIED TO SOME SPACE-TIME MODELS USING EXCALC ALGEBRAIC PROGRAMMING

1994 ◽  
Vol 05 (06) ◽  
pp. 973-985 ◽  
Author(s):  
DUMITRU N. VULCANOV
Keyword(s):  
General Relativity ◽  
Hamiltonian Formulation ◽  
Space Time ◽  
Algebraic Programming ◽  
Constraint Equations ◽  
New Procedures ◽  
Dynamic Variables ◽  
Ibm Pc

This article presents the results obtained with new procedures in REDUCE language using EXCALC package (adapted for IBM-PC machines) for algebraic programming in the Hamiltonian formulation of general relativity (ADM formalism). The procedures calculate the dynamic and the constraint equations and, in addition, we have extended the obtained procedures in order to perform a complete ADM reductional procedure: solving the constraint equations, changing of variables, reduction of dynamic variables, etc. The results obtained after processing some examples of space-time models are presented here.

Algebraic Programming in the Hamiltonian Treatment of the Einstein–Maxwell Equations

1998 ◽  
Vol 09 (01) ◽  
pp. 103-111
Author(s):  
Dumitru N. Vulcanov
Keyword(s):  
Electromagnetic Field ◽  
Maxwell Equations ◽  
Hamiltonian Formulation ◽  
Space Time ◽  
Algebraic Programming ◽  
Constraint Equations ◽  
Free Electromagnetic Field ◽  
New Procedures ◽  
Ibm Pc

We present new procedures in REDUCE language using the EXCALC package (adapted for IBM-PC machines) for algebraic programming in the hamiltonian formulation of Einstein–Maxwell equations. The dynamic and the constraint equations containing specific terms of the interaction of gravity with source-free electromagnetic field are translated into computer procedures. The results obtained by processing some examples of space-time models are presented.

New Routines for Algebraic Programming of the Dirac Equation

1997 ◽  
Vol 08 (02) ◽  
pp. 273-286 ◽  
Author(s):  
Ion I. Cotăescu ◽  
Dumitru N. Vulcanov
Keyword(s):  
Dirac Equation ◽  
Main Part ◽  
Space Time ◽  
Curved Space ◽  
Algebraic Programming ◽  
Matrix Algebras ◽  
Dirac Matrix ◽  
New Procedures

We present new procedures in the REDUCE language for algebraic programming of the Dirac equation on curved space-time. The main part of the program is a package of routines defining the Pauli and Dirac matrix algebras. Then the Dirac equation is obtained using the facilities of the EXCALC package. Finally we present some results obtained after running our procedures for the Dirac equation on several curved space-times.

scholarly journals THE EINSTEIN–CARTAN–MAXWELL THEORY WITH SCALAR FIELD THROUGH A FIVE-DIMENSIONAL UNIFICATION

2000 ◽  
Vol 15 (08) ◽  
pp. 1235-1243 ◽  
Author(s):  
CHRISTOPHER KOHLER
Keyword(s):  
Electromagnetic Field ◽  
Scalar Field ◽  
Dimensional Space ◽  
Space Time ◽  
Action Functional ◽  
Maxwell Theory ◽  
Electromagnetic Field Strength ◽  
Klein Theory ◽  
Dimensional Space Time ◽  
Kaluza Klein

A modification of Kaluza–Klein theory is proposed in which, as a result of a symmetry breaking, five-dimensional space–time is partially parallelized implying the appearance of torsion fields. A naturally chosen action functional leads to the Einstein–Cartan–Maxwell theory where the electromagnetic field strength is represented by the fifth component of the torsion two-form. Incorporation of a scalar field reveals that four-dimensional space–time torsion is not induced by the scalar field.

scholarly journals Favored Inflationary Models by Scalar Field Condensate Baryogenesis

Galaxies ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 49
Author(s):  
Daniela Kirilova ◽  
Mariana Panayotova
Keyword(s):  
Scalar Field ◽  
Baryon Asymmetry ◽  
Inflationary Model ◽  
Inflation Model ◽  
Low Energies ◽  
Inflationary Models ◽  
Chaotic Inflation

We calculate the baryon asymmetry value generated in the Scalar Field Condensate (SCF) baryogenesis model obtained in several inflationary scenarios and different reheating models. We provide analysis of the baryon asymmetry value obtained for more than 70 sets of parameters of the SCF model and the following inflationary scenarios, namely: new inflation, chaotic inflation, Starobinsky inflation, MSSM inflation, quintessential inflation. We considered both cases of efficient thermalization after inflation and delayed thermalization. We have found that the SFC baryogenesis model produces baryon asymmetry orders of magnitude bigger than the observed one for the following inflationary models: new inflation, new inflation model by Shafi and Vilenkin, MSSM inflation, chaotic inflation with high reheating temperature and the simplest Shafi–Vilenkin chaotic inflationary model. Strong diluting mechanisms are needed for these models to reduce the resultant baryon excess at low energies to its observational value today. We have found that a successful generation of the observed baryon asymmetry is possible by the SCF baryogenesis model in Modified Starobinsky inflation, chaotic inflation with low reheating temperature, chaotic inflation in SUGRA, and Quintessential inflation.

CASIMIR EFFECT FOR THE ROBIN SURFACES IN STATIC ROBERTSON–WALKER SPACE–TIME

2011 ◽  
Vol 20 (02) ◽  
pp. 161-168 ◽  
Author(s):  
MOHAMMAD R. SETARE ◽  
M. DEHGHANI
Keyword(s):  
Scalar Field ◽  
Energy Momentum Tensor ◽  
Casimir Effect ◽  
Vacuum Expectation ◽  
Robin Boundary Condition ◽  
Momentum Tensor ◽  
Space Time ◽  
Conformally Invariant ◽  
Time Space ◽  
Robin Boundary

We investigate the energy–momentum tensor for a massless conformally coupled scalar field in the region between two curved surfaces in k = -1 static Robertson–Walker space–time. We assume that the scalar field satisfies the Robin boundary condition on the surfaces. Robertson–Walker space–time space is conformally related to Rindler space; as a result we can obtain vacuum expectation values of the energy–momentum tensor for a conformally invariant field in Robertson–Walker space–time space from the corresponding Rindler counterpart by the conformal transformation.

scholarly journals Janis–Newman–Winicour and Wyman Solutions are the Same

1997 ◽  
Vol 12 (27) ◽  
pp. 4831-4835 ◽  
Author(s):  
K. S. Virbhadra
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Total Energy ◽  
Space Time ◽  
Massless Scalar ◽  
Spherically Symmetric ◽  
Scalar Equations

We show that the well-known most general static and spherically symmetric exact solution to the Einstein-massless scalar equations given by Wyman is the same as one found by Janis, Newman and Winicour several years ago. We obtain the energy associated with this space–time and find that the total energy for the case of the purely scalar field is zero.

scholarly journals WEYL GEOMETRY AS CHARACTERIZATION OF SPACE-TIME

2011 ◽  
Vol 03 ◽  
pp. 87-97 ◽  
Author(s):  
F. P. POULIS ◽  
J. M. SALIM
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Riemannian Geometry ◽  
Axiomatic Approach ◽  
Space Time ◽  
Weyl Geometry ◽  
Test Particles ◽  
Variational Formalism ◽  
Physical Fields

Motivated by an axiomatic approach to characterize space-time it is investigated a reformulation of Einstein's gravity where the pseudo-riemannian geometry is substituted by a Weyl one. It is presented the main properties of the Weyl geometry and it is shown that it gives extra contributions to the trajectories of test particles, serving as one more motivation to study general relativity in Weyl geometry. It is introduced its variational formalism and it is established the coupling with other physical fields in such a way that the theory acquires a gauge symmetry for the geometrical fields. It is shown that this symmetry is still present for the red-shift and it is concluded that for cosmological models it opens the possibility that observations can be fully described by the new geometrical scalar field. It is concluded then that this reformulation, although representing a theoretical advance, still needs a complete description of their objects.

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