23 research outputs found
Non-Abelian brane cosmology
We discuss isotropic and homogeneous D-brane-world cosmology with non-Abelian
Born-Infeld (NBI) matter on the brane. In the usual Friedmann-Robertson-Walker
(FRW) model the scale non-invariant NBI matter gives rise to an equation of
state which asymptotes to the string gas equation and ensures a
start-up of the cosmological expansion with zero acceleration. We show that the
same state equation in the brane-world setup leads to the Tolman type evolution
as if the conformal symmetry was effectively restored. This is not precisely so
in the NBI model with symmetrized trace, but the leading term in the expansion
law is still the same. A cosmological sphaleron solution on the D-brane is
presented.Comment: 6 pages, latex, 1 figure. Submitted to the Proceedings of the VFC
workshop at JENAM2002, Portu, Portugal, 1-6 september 200
Stabilization of the Yang-Mills chaos in non-Abelian Born-Infeld theory
We investigate dynamics of the homogeneous time-dependent SU(2) Yang-Mills
fields governed by the non-Abelian Born-Infeld lagrangian which arises in
superstring theory as a result of summation of all orders in the string slope
parameter . It is shown that generically the Born-Infeld dynamics is
less chaotic than that in the ordinary Yang-Mills theory, and at high enough
field strength the Yang-Mills chaos is stabilized. More generally, a smothering
effect of the string non-locality on behavior of classical fields is
conjectured.Comment: 7 pages, 5 figure
Dyons in Nonabelian Born-Infeld Theory
We analyze a nonabelian extension of Born--Infeld action for the SU(2) group.
In the class of spherically symmetric solutions we find that, besides the
Gal'tsov--Kerner glueballs, only the analytic dyons have finite energy. The
presented analytic and numerical investigation excludes the existence of pure
magnetic monopoles of 't Hooft--Polyakov type.Comment: 12 pages, 3 figure
Rotating Black Branes in the presence of nonlinear electromagnetic field
In this paper, we consider a class of gravity whose action represents itself
as a sum of the usual Einstein-Hilbert action with cosmological constant and an
gauge field for which the action is given by a power of the Maxwell
invariant. We present a class of the rotating black branes with Ricci flat
horizon and show that the presented solutions may be interpreted as black brane
solutions with two event horizons, extreme black hole and naked singularity
provided the parameters of the solutions are chosen suitably. We investigate
the properties of the solutions and find that for the special values of the
nonlinear parameter, the solutions are not asymptotically anti-deSitter. At
last, we obtain the conserved quantities of the rotating black branes and find
that the nonlinear source effects on the electric field, the behavior of
spacetime, type of singularity and other quantities.Comment: 7 pages, 5 figures, to appear in EPJ
Non-linear electrodynamics and the acceleration of the universe
It is shown that the addition of a non-linear term to the Lagrangian of the
electromagnetic field yields a fluid with an asymptotically super-negative
equation of state, causing an accelerated expansion of the universe. Some
general properties of nonlinear electromagnetism in cosmology are also
discussed.Comment: 5 pages, 1 figure, minor modifications to match version to appear in
PR