16 research outputs found
Massive fermion model in 3d and higher spin currents
We analyze the 3d free massive fermion theory coupled to external sources. The presence of a mass explicitly breaks parity invariance. We calculate two- and three-point functions of a gauge current and the energy momentum tensor and, for instance, obtain the well-known result that in the IR limit (but also in the UV one) we reconstruct the relevant CS action. We then couple the model to higher spin currents and explicitly work out the spin 3 case. In the UV limit we obtain an effective action which was proposed many years ago as a possible generalization of spin 3 CS action. In the IR limit we derive a different higher spin action. This analysis can evidently be generalized to higher spins. We also discuss the conservation and properties of the correlators we obtain in the intermediate steps of our derivation
Killing Horizons as Equipotential Hypersurfaces
In this note we present a new proof that Killing horizons are equipotential
hypersurfaces for the electric and the magnetic scalar potential, that makes no
use of gravitational field equations or the assumption about the existence of
bifurcation surface.Comment: 8 pages; revised, published version; several assumptions removed from
the final theore
Gravitational Chern-Simons Lagrangians and black hole entropy
We analyze the problem of defining the black hole entropy when Chern-Simons
terms are present in the action. Extending previous works, we define a general
procedure, valid in any odd dimensions both for purely gravitational CS terms
and for mixed gauge-gravitational ones. The final formula is very similar to
Wald's original formula valid for covariant actions, with a significant
modification. Notwithstanding an apparent violation of covariance we argue that
the entropy formula is indeed covariant.Comment: 39 page
Gravitational Chern-Simons terms and black hole entropy. Global aspects
We discuss the topological and global gauge properties of the formula for a
black hole entropy due to a purely gravitational Chern-Simons term. We study
under what topological and geometrical conditions this formula is well-defined.
To this end we have to analyze the global properties of the Chern-Simons term
itself and the quantization of its coupling. We show that in some cases the
coupling quantization may interfere with the well-definiteness of the entropy
formula.Comment: 37 pages, a few comments and references adde
Dynamical Boson Stars
The idea of stable, localized bundles of energy has strong appeal as a model
for particles. In the 1950s John Wheeler envisioned such bundles as smooth
configurations of electromagnetic energy that he called {\em geons}, but none
were found. Instead, particle-like solutions were found in the late 1960s with
the addition of a scalar field, and these were given the name {\em boson
stars}. Since then, boson stars find use in a wide variety of models as sources
of dark matter, as black hole mimickers, in simple models of binary systems,
and as a tool in finding black holes in higher dimensions with only a single
killing vector. We discuss important varieties of boson stars, their dynamic
properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in
Relativity; major revision in 201