6,173 research outputs found
Power-law corrections to black-hole entropy via entanglement
We consider the entanglement between quantum field degrees of freedom inside
and outside the horizon as a plausible source of black-hole entropy. We examine
possible deviations of black hole entropy from area proportionality. We show
that while the area law holds when the field is in its ground state, a
correction term proportional to a fractional power of area results when the
field is in a superposition of ground and excited states. We compare our
results with the other approaches in the literature.Comment: 10 pages, 5 figures, to appear in the Proceedings of "BH2, Dynamics
and Thermodynamics of Blackholes and Naked Singularities", May 10-12 2007,
Milano, Italy; conference website: http://www.mate.polimi.it/bh2
Gravitational Redshift in Einstein-Kalb-Ramond Spacetime and Randall-Sundrum Scenario
It is shown that the gravitational redshift as predicted by Einstein's
theory, is modified in presence of second rank antisymmetric tensor
(Kalb-Ramond) field in a string inspired background spacetime.In presence of
extra dimensions, the Randall-Sundrum brane world scenario is found to play a
crucial role in suppressing this additional shift. The bound on the value of
the warp factor is determined from the redshift data and is found to be in good
agreement with that determined from the requirements of Standard model.Comment: 4 Pages, Revtex, No figures, version thoroughly revise
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
Where are the degrees of freedom responsible for black hole entropy?
Considering the entanglement between quantum field degrees of freedom inside
and outside the horizon as a plausible source of black hole entropy, we address
the question: {\it where are the degrees of freedom that give rise to this
entropy located?} When the field is in ground state, the black hole area law is
obeyed and the degrees of freedom near the horizon contribute most to the
entropy. However, for excited state, or a superposition of ground state and
excited state, power-law corrections to the area law are obtained, and more
significant contributions from the degrees of freedom far from the horizon are
shown.Comment: 6 pages, 4 figures, Invited talk at Theory Canada III, Edmonton,
Alberta, Canada, June 16, 200
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