39 research outputs found
R-Matrix Formulation of KP Hierarchies and their Gauge Equivalence
The Adler-Kostant-Symes -bracket scheme is applied to the algebra of
pseudo-differential operators to relate the three integrable hierarchies: KP
and its two modifications, known as nonstandard integrable models. All three
hierarchies are shown to be equivalent and connection is established in the
form of a symplectic gauge transformation. This construction results in a new
representation of the W-infinity algebras in terms of 4 bosonic fields.Comment: 13 pages, Latex, CERN-TH.6627/9
Dynamically generated inflationary two-field potential via non-Riemannian volume forms
We consider a simple model of modified gravity interacting with a single
scalar field with weakly coupled exponential potential within the
framework of non-Riemannian spacetime volume-form formalism. The specific form
of the action is fixed by the requirement of invariance under global Weyl-scale
symmetry. Upon passing to the physical Einstein frame we show how the
non-Riemannian volume elements create a second canonical scalar field and
dynamically generate a non-trivial two-scalar-field potential with two remarkable features: (i) it possesses a large flat
region for large describing a slow-roll inflation; (ii) it has a stable
low-lying minimum w.r.t. representing the dark energy density in
the "late universe". We study the corresponding two-field slow-roll inflation
and show that the pertinent slow-roll inflationary curve
in the two-field space has a very small curvature, i.e.,
changes very little during the inflationary evolution of on the
flat region of . Explicit expressions are found for the
slow-roll parameters which differ from those in the single-field inflationary
counterpart. Numerical solutions for the scalar spectral index and the
tensor-to-scalar ratio are derived agreeing with the observational data.Comment: 13 pages. 2 Fig. arXiv admin note: text overlap with arXiv:1906.06691
, v.2 14 pages, typos corrected, additional explanation
Weyl-Conformally-Invariant Lightlike p-Brane Theories: New Aspects in Black Hole Physics and Kaluza-Klein Dynamics
We introduce and study in some detail the properties of a novel class of
Weyl-conformally invariant p-brane theories which describe intrinsically
lightlike branes for any odd world-volume dimension. Their dynamics
significantly differs from that of the ordinary (conformally non-invariant)
Nambu-Goto p-branes. We present explicit solutions of the Weyl-invariant
lightlike brane- (WILL-brane) equations of motion in various gravitational
models of physical relevance exhibiting various new phenomena. In D=4 the
WILL-membrane serves as a material and charged source for gravity and
electromagnetism in the coupled Einstein-Maxwell-WILL-membrane system; it
automatically positions itself on (``straddles'') the common event horizon of
the corresponding matching black hole solutions, thus providing an explicit
dynamical realization of the membrane paradigm in black hole physics. In
product spaces of interest in Kaluza-Klein theories the WILL-brane wraps
non-trivially around the compact (internal)dimensions and still describes
massless mode dynamics in the non-compact (space-time) dimensions. Due to
nontrivial variable size of the internal compact dimensions we find new types
of physically interesting solutions describing massless brane modes trapped on
bounded planar circular orbits with non-trivial angular momentum, and with
linear dependence between energy and angular momentum.Comment: 28 pages, published versio
Fully Explorable Horned Particles Hiding Charge
The charge-hiding effect by a horned particle, which was studied for the case
where gravity/gauge-field system is self-consistently interacting with a
charged lightlike brane (LLB) as a matter source, is now studied for the case
of a time like brane. From the demand that no surfaces of infinite coordinate
time redshift (horizons) appear in the problem we are lead now to a completly
explorable horned particle space for traveller that goes through the horned
particle (as was the case for the LLB) but now also in addition to this, the
horned region is fully visible to a static external observer. This requires
negative surface energy density for the shell sitting at the throat. We study a
gauge field subsystem which is of a special non-linear form containing a
square-root of the Maxwell term and which previously has been shown to produce
a QCD-like confining gauge field dynamics in flat space-time. The condition of
finite energy of the system or asymptotic flatness on one side of the horned
particle implies that the charged object sitting at the throat expels all the
flux it produces into the other side of the horned particle, which turns out to
be of a "tube-like" nature. An outside observer in the asymptotically flat
universe detects, therefore, apparently neutral object. The hiding of the
electric flux behind the tube-like region of a horned particle is the only
possible way that a truly charged particle can still be of finite energy, in a
theory that in flat space describes confinement. This points to the physical
relevance of such solutions, even though there is the need of negative energy
density at the throat of the horned particle, which can be of quantum
mechanical origin.Comment: The new version has been accepted for publication in Classical and
Quantum Gravity. Title changed to "Fully Explorable Horned Particles Hiding
Charge". Horned Particles terminology is used now instead of "wormholes" to
dscribe the solutions here. arXiv admin note: text overlap with
arXiv:1108.373