48 research outputs found
Membrane Pregeometry and the Vanishing of the Cosmological Constant
We suggest a model of induced gravity in which the fundamental object is a
relativistic {\it membrane} minimally coupled to a background metric and to an
external three index gauge potential. We compute the low energy limit of the
two-loop effective action as a power expansion in the surface tension. A
generalized bootstrap hypothesis is made in order to identify the physical
metric and gauge field with the lowest order terms in the expansion of the
vacuum average of the composite operators conjugate to the background fields.
We find that the large distance behaviour of these classical fields is
described by the Einstein action with a cosmological term plus a Maxwell type
action for the gauge potential. The Maxwell term enables us to apply the
Hawking-Baum argument to show that the physical cosmological constant is
``~probably~'' zero.Comment: 14 pages, no figures, phyzzx macr
Dualization of non-Abelian BF model
We show that dualization of BF models to Stueckelberg-like massive gauge
theories allows a non-Abelian extension. We obtain local Lagrangians which are
straightforward extensions of the Abelian results.Comment: 6 pages, ReVTeX, no figures, to be publ. on Phys.Lett.
Gravitational and Schwinger model anomalies: how far can the analogy go?
We describe the most general treatment of all anomalies both for chiral and
massless Dirac fermions, in two-dimensional gravity. It is shown that for this
purpose two regularization dependent parameters are present in the effective
action. Analogy to the \sc\ model is displayed corresponding to a specific
choice of the second parameter, thus showing that the gravitational model
contains \a\ relations having no analogy in the \sc\ model.Comment: 16 pages, no figure, phyzzx macro, square.tex has been deleted from
the previous versio
Duality of massive gauge invariant theories in arbitrary space-time dimension
We show that dualization of Stueckelberg-like massive gauge theories and
models, follows form a general p-dualization of interacting
theories in d spacetime dimensions. This is achieved by a particular choice of
the external current.Comment: ReVTeX 7pages, no figures, accepted for publ. in Phys.Rev.
Dualization of Interacting Theories Including p=d-1 Limiting Cases
We study the vacuum partition functional Z [J] for a system of closed, bosonic p-branes coupled to p-forms in the limiting case: p+1 = space-time dimension. We suggest an extension of the duality transformation which can be applied to the limiting case even though no dual gauge potential exists in the conventional sense. The dual action thus obtained describes a current-current, static interaction within the bulk volume bounded by the d-1-brane. Guided by these results, we then construct a general expression for the parent Lagrangian that allows for a unified treatment of p-duality, even in the presence of external currents, using a first order formalism instead of the Bianchi identities. Finally, we show how this generalized dualization approach can accommodate the inclusion of a massive topological term in the parent action of an Abelian gauge theory
A model of radiating black hole in noncommutative geometry
The phenomenology of a radiating Schwarzschild black hole is analyzed in a
noncommutative spacetime. It is shown that noncommutativity does not depend on
the intensity of the curvature. Thus we legitimately introduce noncommutativity
in the weak field limit by a coordinate coherent state approach. The new
interesting results are the following: i) the existence of a minimal non-zero
mass to which black hole can shrink; ii) a finite maximum temperature that the
black hole can reach before cooling down to absolute zero; iii) the absence of
any curvature singularity. The proposed scenario offers a possible solution to
conventional difficulties when describing terminal phase of black hole
evaporation.Comment: 10 pages, 4 figure