7,938 research outputs found
Non-Chern-Simons Topological Mass Generation in (2+1) Dimensions
By dimensional reduction of a massive BF theory, a new topological field
theory is constructed in (2+1) dimensions. Two different topological terms, one
involving a scalar and a Kalb-Ramond fields and another one equivalent to the
four-dimensional BF term, are present. We constructed two actions with these
topological terms and show that a topological mass generation mechanism can be
implemented. Using the non-Chern-Simons topological term, an action is proposed
leading to a classical duality relation between Klein-Gordon and Maxwell
actions. We also have shown that an action in (2+1) dimensions with the
Kalb-Ramond field is related by Buscher's duality transformation to a massive
gauge-invariant Stuckelberg-type theory.Comment: 8 pages, no figures, RevTE
Causal Structure and Birefringence in Nonlinear Electrodynamics
We investigate the causal structure of general nonlinear electrodynamics and
determine which Lagrangians generate an effective metric conformal to
Minkowski. We also proof that there is only one analytic nonlinear
electrodynamics presenting no birefringence.Comment: 11 pages, no figure
Mass generation for non-Abelian antisymmetric tensor fields in a three-dimensional space-time
Starting from a recently proposed Abelian topological model in (2+1)
dimensions, which involve the Kalb-Ramond two form field, we study a
non-Abelian generalization of the model. An obstruction for generalization is
detected. However we show that the goal is achieved if we introduce a vectorial
auxiliary field. Consequently, a model is proposed, exhibiting a non-Abelian
topological mass generation mechanism in D=3, that provides mass for the
Kalb-Ramond field. The covariant quantization of this model requires ghosts for
ghosts. Therefore in order to quantize the theory we construct a complete set
of BRST and anti-BRST equations using the horizontality condition.Comment: 8 pages. To appear in Physical Review
Bopp-Podolsky black holes and the no-hair theorem
Bopp-Podolsky electrodynamics is generalized to curved space-times. The
equations of motion are written for the case of static spherically symmetric
black holes and their exterior solutions are analyzed using Bekenstein's
method. It is shown the solutions split-up into two parts, namely a
non-homogeneous (asymptotically massless) regime and a homogeneous
(asymptotically massive) sector which is null outside the event horizon. In
addition, in the simplest approach to Bopp-Podolsky black holes, the
non-homogeneous solutions are found to be Maxwell's solutions leading to a
Reissner-Nordstr\"om black hole. It is also demonstrated that the only exterior
solution consistent with the weak and null energy conditions is the Maxwell's
one. Thus, in light of energy conditions, it is concluded that only Maxwell
modes propagate outside the horizon and, therefore, the no-hair theorem is
satisfied in the case of Bopp-Podolsky fields in spherically symmetric
space-times.Comment: 9 pages, updated to match published versio
de Broglie-Proca and Bopp-Podolsky massive photon gases in cosmology
We investigate the influence of massive photons on the evolution of the
expanding universe. Two particular models for generalized electrodynamics are
considered, namely de Broglie-Proca and Bopp-Podolsky electrodynamics. We
obtain the equation of state (EOS) for each case using
dispersion relations derived from both theories. The EOS are inputted into the
Friedmann equations of a homogeneous and isotropic space-time to determine the
cosmic scale factor . It is shown that the photon non-null mass does not
significantly alter the result valid for a massless photon
gas; this is true either in de Broglie-Proca's case (where the photon mass
is extremely small) or in Bopp-Podolsky theory (for which is extremely
large).Comment: 8 pages, 2 figures; v2 matches the published versio
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