98,003 research outputs found
Some consequences of the effective low-energy lagrangian for gravity
We consider the minimal low-energy action for gravity up to six derivatives
which is renormalizable at the two-loop level modulo higher derivative
corrections. Then we study the classical solutions corresponding to the
Schwarzschild and the Robertson-Walker metrics. In the first case we find a
singularity close to the gravitational radius and in the second case we find
inflationary de Sitter solutions in absence of any matter or cosmological
constant.Comment: 13 page
Area spectrum of the d-dimensional Reissner-Nordstrom black hole in the small charge limit
A conjecture by Hod states that for the black hole horizon the spacing of its
area spectrum is determined by the asymptotic value of its quasinormal
frequencies. Recently to overcome some difficulties, Maggiore proposes some
changes to the original Hod's conjecture. Taking into account the modifications
proposed by Maggiore we calculate the area spectrum of the d-dimensional
Reissner-Nordstrom black hole in the small charge limit.Comment: 11 page
Area spectrum of the D-dimensional de Sitter spacetime
The determination of the quantum area spectrum of a black hole horizon by
means of its asymptotic quasinormal frequencies has been explored recently. We
believe that for D-dimensional de Sitter horizon we must study if the idea
works. Thus taking into account the local description of the thermodynamics of
horizons proposed by Padmanabhan and the results of Hod, Kunstatter, and
Maggiore we study the area spectrum of the D-dimensional de Sitter horizon.Comment: 6 pages, accepted for publication in Physics Letters
On the Time Times Temperature Bound
Recently Hod proposes a lower bound on the relaxation time of a perturbed
thermodynamic system. For gravitational systems this bound transforms into a
condition on the fundamental quasinormal frequency. We test the bound in some
spacetimes whose quasinormal frequencies are calculated exactly, as the
three-dimensional BTZ black hole, the D-dimensional de Sitter spacetime, and
the D-dimensional Nariai spacetime. We find that for some of these spacetimes
their fundamental quasinormal frequencies do not satisfy the bound proposed by
Hod.Comment: 11 page
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