677 research outputs found
Integrability and Symmetry Algebra Associated with N=2 KP Flows
We show the complete integrability of N=2 nonstandard KP flows establishing
the biHamiltonian structures. One of Hamiltonian structures is shown to be
isomorphic to the nonlinear N=2 algebra with the bosonic
sector having structure. A consistent
free field representation of the super conformal algebra is obtained. The
bosonic generators are found to be an admixture of free fermions and free
complex bosons, unlike the linear one. The fermionic generators become
exponential in free fields, in general.Comment: Latex file, 38 pages, no figure
Axially symmetric, asymptotically flat vacuum metric with a naked singularity and closed timelike curves
We present an axially symmetric, asymptotically flat empty space solution of
the Einstein field equations containing a naked singularity. The spacetime is
regular everywhere except on the symmetry axis where it possess a true
curvature singularity. The spacetime is of type D in the Petrov classification
scheme and is locally isometric to the metrics of case IV in the Kinnersley
classification of type D vacuum metrics. Additionally, the spacetime also shows
the evolution of closed timelike curves (CTCs) from an initial hypersurface
free from CTCs.Comment: 8 pages, no figure
Generalized form of exponential wormhole metric
In this work we have formulated a general exponential wormhole metric. Here
initially we have considered a exponential wormhole metric in which the
temporal component is an exponential function of but the spatial components
of the metrics are fixed as a particular function .
Following that, we have constructed a generalised exponential wormhole metric
in which the spatial component is an exponential function of but the
temporal component is fixed as a particular function given by
. Finally we have considered exponential metric in
which both the temporal and spatial components are generalised exponential
function of . We have also studied some of their properties including throat
radius, energy conditions, the metric in curvature coordinates, effective
refractive index, ISCO and photon sphere, Regge-Wheeler potential and
determined the curvature tensor. The radius of the throat is found to be
consistent with the properties of wormholes, which are given by , , ...etc. Most interestingly, their throat radius is same for the
same spatial component and the same range of values of . In addition to
these they also violate Null Energy Condition(NEC) near the throat
Study of exponential wormhole metric in gravity
In this work, we have studied an "exponential form" of spacetime metric:
\begin{equation*} ds^2 = -e^{-\frac{2m}{r}}dt^2 +e^{\frac{2m}{r}}dr^2 +
e^{\frac{2m}{r}}[r^2 d\theta^2 + r^2 \sin^2\theta d\phi^2] \end{equation*} in
some of the viable gravity models, viz. exponential gravity model,
Starobinsky gravity model, Tsujikawa model and Gogoi-Goswami f(R) gravity
model. Here we have calculated the parameters including energy density,
tangential and radial pressure for these corresponding models of
gravity. Subsequently we have investigated the energy conditions viz. null
energy condition(NEC), weak energy condition(WEC) and strong energy
condition(SEC) for the considered models. We have also explained the suitable
conditions of energy for these models by related plots
Axial symmetry cosmological constant vacuum solution of field equations with a curvature singularity, closed time-like curves and deviation of geodesics
In this paper, we present a type D, non-vanishing cosmological constant,
vacuum solution of the Einstein's field equations, extension of an axially
symmetric, asymptotically flat vacuum metric with a curvature singularity. The
space-time admits closed time-like curves (CTCs) that appear after a certain
instant of time from an initial spacelike hypersurface, indicating it
represents a time-machine space-time. We wish to discuss the physical
properties and show that this solution can be interpreted as gravitational
waves of Coulomb-type propagate on anti-de Sitter space backgrounds. Our
treatment focuses on the analysis of the equation of geodesic deviation.Comment: 17 pages, accepted for publication in Adv. High Energy Physics
journa
Constructing a Supersymmetric Integrable System from the Hirota Method in Superspace
An N=1 supersymmetric system is constructed and its integrability is shown by
obtaining three soliton solutions for it using the supersymmetric version of
Hirota's direct method.Comment: 10 pages, no figure
- β¦