6,102 research outputs found
Universal near-horizon conformal structure and black hole entropy
It is shown that a massless scalar probe reveals a universal near-horizon
conformal structure for a wide class of black holes, including the BTZ. The
central charge of the corresponding Virasoro algebra contains information about
the black hole. With a suitable quantization condition on the central charge,
the CFT associated with the black hole in our approach is consistent with the
recent observation of Witten, where the dual theory for the BTZ in the AdS/CFT
framework has been identified with the construction of Frenkel, Lepowsky and
Meurman. This CFT admits the Fischer-Griess monster group as its symmetry. The
logarithm of the dimension of a specific representation of the monster group
has been identified by Witten as the entropy of the BTZ black hole. Our
algebraic approach shows that a wide class of black holes share the same
near-horizon conformal structure as that for the BTZ. With a suitable
quantization condition, the CFT's for all these black holes in our formalism
can be identified with the FLM model, although not through the AdS/CFT
correspondence. The corresponding entropy for the BTZ provides a lower bound
for the entropy of this entire class of black holes.Comment: References updated, text rearrange
Characterization and comparative evaluation of novel planar electromagnetic sensors
The characterization of three types of novel planar electromagnetic sensors: 1) meander; 2) mesh; and 3) interdigital configuration, has been studied and their comparative performance has been evaluated based on their areas of applications. All of them are suitable for inspection and evaluation of system properties without destroying them. The experiments on fabricated sensors have been conducted and the results are presented here. The target application is to use a mixture of different types of sensors to detect plasti
Spherically Symmetric Solutions of Gravitational Field Equations in Kalb-Ramond Background
Static spherically symmetric solution in a background spacetime with torsion is derived explicitly. The torsion considered here is identified with the field strength of a second rank antisymmetric tensor field namely the Kalb-Ramond field and the proposed solution therefore has much significance in a string inspired gravitational field theory
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