2,354 research outputs found
Relativistic Green functions in a plane wave gravitational background
We consider a massive relativistic particle in the background of a
gravitational plane wave. The corresponding Green functions for both spinless
and spin 1/2 cases, previously computed by A. Barducci and R. Giachetti
\cite{Barducci3}, are reobtained here by alternative methods, as for example,
the Fock-Schwinger proper-time method and the algebraic method. In analogy to
the electromagnetic case, we show that for a gravitational plane wave
background a semiclassical approach is also sufficient to provide the exact
result, though the lagrangian involved is far from being a quadratic one.Comment: Last paper by Professor Arvind Narayan Vaidya, 18 pages, no figure
A Conformal Mapping and Isothermal Perfect Fluid Model
Instead of conformal to flat spacetime, we take the metric conformal to a
spacetime which can be thought of as ``minimally'' curved in the sense that
free particles experience no gravitational force yet it has non-zero curvature.
The base spacetime can be written in the Kerr-Schild form in spherical polar
coordinates. The conformal metric then admits the unique three parameter family
of perfect fluid solution which is static and inhomogeneous. The density and
pressure fall off in the curvature radial coordinates as for
unbounded cosmological model with a barotropic equation of state. This is the
characteristic of isothermal fluid. We thus have an ansatz for isothermal
perfect fluid model. The solution can also represent bounded fluid spheres.Comment: 10 pages, TeX versio
Black Holes in Non-flat Backgrounds: the Schwarzschild Black Hole in the Einstein Universe
As an example of a black hole in a non-flat background a composite static
spacetime is constructed. It comprises a vacuum Schwarzschild spacetime for the
interior of the black hole across whose horizon it is matched on to the
spacetime of Vaidya representing a black hole in the background of the Einstein
universe. The scale length of the exterior sets a maximum to the black hole
mass. To obtain a non-singular exterior, the Vaidya metric is matched to an
Einstein universe. The behaviour of scalar waves is studied in this composite
model.Comment: 8 pages, 3 postscript figures, minor corrections Journal Ref:
accepted for Physical Review
SYNTHESIS AND STRUCTURAL STUDIES OF 1-[(8-NITRONAPHTHO[2,1-B]FURAN-2-YL) CARBONYL] PIPERIDINE
Naphtho [2,1-b] furan-2-carboxyazide has been synthesized from ethyl 8-nitronaphtho [2,1-b] furan-2-carboxylate, by first converting into 8-nitronaphtho [2,1-b] furan-2-carboxyhydrazide , followed by diazotization. The reaction of carboxyazide with piperidine resulted in nucleophilic substitution reaction giving 1- [(8-nitronaphtho [2, 1-b] furan-2-yl) carbonyl] piperidine (NNFCP). The compound has been characterized by FT-IR, 1HNMR, Mass spectral data and X-ray diffraction analysis
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
In the context of a noncommutative model of coordinate coherent states, we
present a Schwarzschild-like metric for a Vaidya solution instead of the
standard Eddington-Finkelstein metric. This leads to the appearance of an exact
dependent case of the metric. We analyze the resulting metric in
three possible causal structures. In this setup, we find a zero remnant mass in
the long-time limit, i.e. an instable black hole remnant. We also study the
tunneling process across the quantum horizon of such a Vaidya black hole. The
tunneling probability including the time-dependent part is obtained by using
the tunneling method proposed by Parikh and Wilczek in terms of the
noncommutative parameter . After that, we calculate the entropy
associated to this noncommutative black hole solution. However the corrections
are fundamentally trifling; one could respect this as a consequence of quantum
inspection at the level of semiclassical quantum gravity.Comment: 19 pages, 5 figure
The equations of fit in general relativity
This article does not have an abstract
Current Oscillations, Interacting Hall Discs and Boundary CFTs
In this paper, we discuss the behavior of conformal field theories
interacting at a single point. The edge states of the quantum Hall effect (QHE)
system give rise to a particular representation of a chiral Kac-Moody current
algebra. We show that in the case of QHE systems interacting at one point we
obtain a ``twisted'' representation of the current algebra. The condition for
stationarity of currents is the same as the classical Kirchoff's law applied to
the currents at the interaction point. We find that in the case of two discs
touching at one point, since the currents are chiral, they are not stationary
and one obtains current oscillations between the two discs. We determine the
frequency of these oscillations in terms of an effective parameter
characterizing the interaction. The chiral conformal field theories can be
represented in terms of bosonic Lagrangians with a boundary interaction. We
discuss how these one point interactions can be represented as boundary
conditions on fields, and how the requirement of chirality leads to
restrictions on the interactions described by these Lagrangians. By gauging
these models we find that the theory is naturally coupled to a Chern-Simons
gauge theory in 2+1 dimensions, and this coupling is completely determined by
the requirement of anomaly cancellation.Comment: 32 pages, LateX. Uses amstex, amssymb. Typos corrected. To appear in
Int. J. Mod. Phys.
Whale shark landings in Uttar Kannada, Karnataka
The whale shark, Rhincodon typus Smith, 1828,
has a circumglobal distribution in tropical and warm
temperate seas. Since May 2003 it has been included
under Appendix II of CITES, making the trade of this
species regulated. The status of this species has
since then been upgraded from “Data deficient” in
1996 to “Vulnerable” in 2000 by the IUCN. Currently
it is protected under Schedule I Part II of the Wildlife
Protection Act of India, 1972
Local correlations in a strongly interacting 1D Bose gas
We develop an analytical method for calculating local correlations in
strongly interacting 1D Bose gases, based on the exactly solvable Lieb-Liniger
model. The results are obtained at zero and finite temperatures. They describe
the interaction-induced reduction of local many-body correlation functions and
can be used for achieving and identifying the strong-coupling Tonks-Girardeau
regime in experiments with cold Bose gases in the 1D regime.Comment: 8 pages, REVTeX4, published in the New Journal of Physic
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