48 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
Solitons and black holes in non-Abelian Einstein-Born-Infeld theory
Recently it was shown that the Born-Infeld-type modification of the quadratic
Yang-Mills action gives rise to classical particle-like solutions in the flat
space which have a striking similarity with the Bartnik-McKinnon solutions
known in the gravity coupled Yang-Mills theory. We show that both families are
continuously related within the framework of the Einstein-Born-Infeld theory
through interpolating sequences of parameters. We also investigate an internal
structure of the associated black holes. It is found that the Born-Infeld
non-linearity leads to a drastic modification of the black hole interior
typical for the usual Yang-Mills theory. In the latter case a generic solution
exhibits violent metric oscillations near the singularity. In the Born-Infeld
case a generic interior solution is smooth, the metric has the standard
Schwarzschild type singularity, and we did not observe internal horizons. Such
smoothing of the 'violent' EYM singularity may be interpreted as a result of
quantum effects.Comment: Latex, 9 pages, 9 eps figure
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
The Born-Infeld Sphaleron
We study the SU(2) electroweak model in which the standard Yang-Mills
coupling is supplemented by a Born-Infeld term. The deformation of the
sphaleron and bisphaleron solutions due to the Born-Infeld term is investigated
and new branches of solutions are exhibited. Especially, we find a new branch
of solutions connecting the Born-Infeld sphaleron to the first solution of the
Kerner-Gal'tsov series.Comment: 8 pages, 5 Postscript figures; new results on Bisphalerons added;
minor modification
Sphaleron glueballs in NBI theory with symmetrized trace
We derive a closed expression for the SU(2) Born-Infeld action with the
symmetrized trace for static spherically symmetric purely magnetic
configurations. The lagrangian is obtained in terms of elementary functions.
Using it, we investigate glueball solutions to the flat space NBI theory and
their self-gravitating counterparts. Such solutions, found previously in the
NBI model with the 'square root - ordinary trace' lagrangian, are shown to
persist in the theory with the symmetrized trace lagrangian as well. Although
the symmetrized trace NBI equations differ substantially from those of the
theory with the ordinary trace, a qualitative picture of glueballs remains
essentially the same. Gravity further reduces the difference between solutions
in these two models, and, for sufficiently large values of the effective
gravitational coupling, solutions tends to the same limiting form. The black
holes in the NBI theory with the symmetrized trace are also discussed.Comment: 19 pages,6 eps figures, late