Articles written in Pramana – Journal of Physics
Volume 34 Issue 1 January 1990 pp 1-11
Some cosmological solutions of massive strings are obtained in Bianchi I space-time following the techniques used by Letelier and Stachel. A class of solutions corresponds to string cosmology associated with/without a magnetic field and the other class consists of pure massive strings, obeying the Takabayashi equation of state
Volume 34 Issue 5 May 1990 pp 403-414
A brief account for the higher order wave function in Hartle-Hawking (H-H) proposal is given which is compared with the tunneling wave function due to Vilenkin. The probability distributions are determined for both types of wave functions. Also a class of solutions are evaluated using H-H approach for Kantowski-Sachs metric with a scalar field and inflation is observed.
Volume 39 Issue 3 September 1992 pp 265-271 Research Articles
Classical and quantum cosmological aspects for (
Volume 40 Issue 3 March 1993 pp 207-212
Some cosmological solutions for string model are derived in higher dimensional spherically symmetric space-time, following the techniques used by Letelier. The equations of state for strings have been used for different solutions. Also polynomial relation between the metric coefficients has been assumed in some cases.
Volume 43 Issue 6 December 1994 pp 503-508 Addendum
A study on string theory has been done in five dimensional flat space-time. Barotropic equation of state and
Volume 44 Issue 6 June 1995 pp 495-500
We study spherically symmetric inhomogeneous cosmological model with heat flow in higher dimensional space-time and present a class of solutions in which the velocity field is shear-free. Some of these solutions are analogous to the known solutions in 4-dimension while some are totally new.
Volume 49 Issue 6 December 1997 pp 603-607
We present a detailed analysis of the motion of test particles around domain walls. The study of the trajectories of the test particles has been done using the Hamilton-Jacobi formalism. In most of the cases we show that the particles can not be trapped by the walls.
Volume 51 Issue 3-4 September 1998 pp 369-376 Research Articles
String-dust cosmology in an inhomogeneous cylindrically symmetric model is considered. Solutions are obtained only for geometric string with the separability assumption for metric coefficients.
Volume 51 Issue 6 December 1998 pp 689-692
A detailed analysis of the motion of test particles around global monopole in Brans-Dicke theory of gravity has been prescribed using the Hamilton-Jacobi (H-J) formalism. The trajectory of the test particles are trapped by the monopole with some restriction on the coupling parameter ω.
Volume 56 Issue 5 May 2001 pp 597-604 Research Articles
In this paper, we have studied generalized scalar tensor theory for spherically symmetric models, both in four and higher dimensions with a bulk viscous fluid. We have considered both exponential and power law solutions with some assumptions among the physical parameters and solutions have been discussed.
Volume 58 Issue 1 January 2002 pp 1-12 Research Articles
Using non-minimally coupled scalar-tensor theory in homogeneous and isotropic cosmological model, quantum cosmology has been developed for Ashtekar variables. The wave function has been evaluated by solving the Wheeler-Dewitt (WD) equation and also using path integral formulation. Semi-classical limit using WKB approximation has also been discussed. Finally, the quantum Bohmian trajectories has been studied in detail.
Volume 58 Issue 1 January 2002 pp 113-119 Brief Reports
We present a detailed analysis of the motion of test particle in the gravitational field of cosmic strings in different situations using the Hamilton-Jacobi (H-J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans-Dicke theory and cosmic string in dilaton gravity.
Volume 58 Issue 1 January 2002 pp 121-126 Brief Reports
The gravitational field of a higher dimensional global monopole in the context of Brans-Dicke theory of gravity is investigated. The space time metric and the scalar field generated by a global monopole are obtained using the weak field approximation. Finally, the geodesic of a test particle due to the gravitational field of the monopole is studied.
Volume 61 Issue 4 October 2003 pp 669-673 Reasearch Articles
In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski-Sachs space-time. For bulk viscous fluid, both exponential and power-law solutions have been studied and some assumptions among the physical parameters and solutions have been discussed.
Volume 90 Issue 2 February 2018 Article ID 0019 Research Article
Considering a homogeneous and isotropic Universe characterised by the Friedmann–Lemaître– Robertson–Walker line element, in this work, we have prescribed a general formalism for the cosmological solutions when the equation of state of the cosmic substance follows the general structure $\phi(p, \rho) = 0$, where $p$, $\rho$ are respectively the pressure and the energy density of the cosmic substance. Using the general formalism we recover some well-known solutions, namely, when the cosmic substance obeys the linear equation of state, a Chaplygin-type equation of state, or a nonlinear equation of state. Thus, the current work offers a new technique to solve the cosmological solutions without any prior relation between $p$ and $/rho$.
Volume 94, 2020
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