Bianchi type-I models with conformally invariant scalar field with trace-free energy-momentum tensor

A study of Bianchi Type I cosmological model is undertaken in the framework of creation of particles. To accommodate the creation of new particles, the universe is regarded as an Open thermodynamical system. The energy conservation equation is modified with the incorporation of a creation pressure in the energy momentum tensor. Exact solutions of the field equations are obtained (i) for a particular choice of the particle creation function and (ii) by considering the deceleration parameter to be constant. In the first model the behavior of the solution at late times is investigated. The physical aspects of the model have also been discussed. In the case of the second model we have restricted our analysis to the power law behaviour for the average scale factor. This leads to a particular form for the particle creation function. The behavior of the solution is investigated and the physical aspects of the model have also been discussed for the matter dominated era.

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Homothetic matter collineations of LRS Bianchi type I spacetimes

Modern Physics Letters A ◽

10.1142/s0217732317501978 ◽

2017 ◽

Vol 32 (37) ◽

pp. 1750197 ◽

Cited By ~ 2

Author(s):

Tahir Hussain ◽

Waqas Rahim

Keyword(s):

Bianchi Type ◽

Energy Momentum Tensor ◽

Complete Classification ◽

Momentum Tensor ◽

Type I ◽

Bianchi Type I ◽

Matter Collineations ◽

Rotationally Symmetric ◽

Integrability Conditions

A complete classification of locally rotationally symmetric (LRS) Bianchi type I spacetimes via homothetic matter collineations (HMCs) is presented. For non-degenerate energy–momentum tensor, a general form of the vector field generating HMCs is found, subject to some integrability conditions. Solving the integrability conditions in different cases, it is found that the LRS Bianchi type I spacetimes admit 6-, 7-, 8-, 10- or 11-dimensional Lie algebra of HMCs. When the energy–momentum tensor is degenerate, two cases give 6 and 11 HMCs, while the remaining cases produce infinite number of HMCs. Some LRS Bianchi type I metrics are provided admitting HMCs.

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

International Journal of Modern Physics D ◽

10.1142/s0218271811018767 ◽

2011 ◽

Vol 20 (02) ◽

pp. 161-168 ◽

Cited By ~ 1

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.

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