65 research outputs found
Partition function of massless scalar field in Schwarzschild background
Using thermal value of zeta function instead of zero temperature, the
partition function of quantized fields in arbitrary stationary backgrounds was
found to be independent of undetermined regularization constant in
even-dimension and the long drawn problem associated with the trace anomaly
effect had been removed. Here, we explicitly calculate the expression for the
coincidence limit so that the technique may be applied in some specific
problems. A particular problem dealt with here is to calculate the partition
function of massless scalar field in Schwarzschild background.Comment: 14 pages in Quantum Stud.: Math. Found. (2014
Intermediate inflation or late time acceleration?
The expansion rate of `Intermediate inflation' lies between the exponential
and power law expansion but corresponding accelerated expansion does not start
at the onset of cosmological evolution. Present study of `Intermediate
inflation' reveals that it admits scaling solution and has got a natural exit
form it at a later epoch of cosmic evolution, leading to late time
acceleration. The corresponding scalar field responsible for such feature is
also found to be a tracker field for both gravity with canonical and some
non-canonical form of kinetic term. Thus the so called Intermediate inflation
should be considered as yet another dark energy model with asymptotic de-Sitter
expansion.Comment: 10 page
Noether and some other dynamical symmetries in Kantowski-Sachs model
The forms of coupling of the scalar field with gravity, appearing in the
induced theory of gravity, and the potential are found in the Kantowski-Sachs
model under the assumption that the Lagrangian admits Noether symmetry. The
form thus obtained makes the Lagrangian degenerate. The constrained dynamics
thus evolved due to such degeneracy has been analysed and a solution has also
been presented which is inflationary in behaviour. It has further been shown
that there exists other technique to explore the dynamical symmetries of the
Lagrangian and that is simply by inspecting the field equations. Through this
method, Noether along with some other dynamical symmetries are found, which do
not make the Lagrangian degenerate.Comment: 7 pages,Late
Hamiltonian formulation of curvature squared action
It has been observed earlier that, in principle, it is possible to obtain a
quantum mechanical interpretation of higher order quantum cosmological models
in the spatially homogeneous and isotropic background, if auxiliary variable
required for the Hamiltonian formulation of the theory is chosen properly. It
was suggested that for such a choice, it is required to get rid of all the
total derivative terms from the action containing higher order curvature
invariant terms, prior to the introduction of auxiliary variable. Here, the
earlier work has been modified and it is shown that the action, should be supplemented by a boundary term in the form
, where, , and are the
Ricci scalar for three-space, trace of the extrinsic curvature and determinant
of the metric on the three space respectively. The result has been tested in
the background of homogeneous and anisotropic models and thus confirmed.Comment: 15 pages, late
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