321 research outputs found
Bulk metric of brane world models and submanifolds in 6D pseudo-Euclidean space-time
In this short note, five-dimensional brane world models with dS_{4} metric on
the branes are discussed. The explicit coordinate transformations, which show
the equivalence between the bulk metric of these brane world models and the
metric induced on an appropriate submanifolds in the flat six-dimensional
pseudo-Euclidean space-time, are presented. The cases of the zero and non-zero
cosmological constant in the bulk are discussed in detail.Comment: 5 pages, typos correcte
Classical behaviour of Q-balls in the Wick-Cutkosky model
In this paper, we continue discussing Q-balls in the Wick--Cutkosky model.
Despite Q-balls in this model are composed of two scalar fields, they turn out
to be very useful and illustrative for examining various important properties
of Q-balls. In particular, in the present paper we study in detail
(analytically and numerically) the problem of classical stability of Q-balls,
including the nonlinear evolution of classically unstable Q-balls, as well as
the behaviour of Q-balls in external fields in the non-relativistic limit.Comment: 21 pages, 12 figures, LaTeX; v2: section 3.3 slightly enlarged, typos
corrected, minor changes in the tex
Fast Zonal Field Dynamo in Collisionless Kinetic Alfven Wave Turbulence
The possibility of fast dynamo action by collisionless kinetic Alfven Wave
turbulence is demonstrated. The irreversibility necessary to lock in the
generated field is provided by electron Landau damping, so the induced electric
field does not vanish with resistivity. Mechanisms for self-regulation of the
system and the relation of these results to the theory of alpha quenching are
discussed. The dynamo-generated fields have symmetry like to that of zonal
flows, and thus are termed zonal fields
Two-fluid magnetic island dynamics in slab geometry: I - Isolated islands
A set of reduced, 2-D, two-fluid, drift-MHD equations is derived. Using these
equations, a complete and fully self-consistent solution is obtained for an
isolated magnetic island propagating through a slab plasma with uniform but
different ion and electron fluid velocities. The ion and electron fluid flow
profiles around the island are uniquely determined, and are everywhere
continuous. Moreover, the island phase-velocity is uniquely specified by the
condition that there be zero net electromagnetic force acting on the island.
Finally, the ion polarization current correction to the Rutherford island width
evolution equation is evaluated, and found to be stabilizing provided that the
anomalous perpendicular ion viscosity significantly exceeds the anomalous
perpendicular electron viscosity
Q-holes
We consider localized soliton-like solutions in the presence of a stable
scalar condensate background. By the analogy with classical mechanics, it can
be shown that there may exist solutions of the nonlinear equations of motion
that describe dips or rises in the spatially-uniform charge distribution. We
also present explicit analytical solutions for some of such objects and examine
their properties.Comment: 17 pages, 11 figures, LaTeX. v3: minor corrections in the tex
The specificity of searches for , and coming from extra dimensions
We discuss the specificity of searches for hypothetical ,
and bosons at hadron colliders in single top
quark and production and Drell-Yan processes assuming these
particles to be the Kaluza-Klein excitations of the gauge bosons of the
Standard Model. In this case any process mediated by is also mediated by
the whole KK tower of its excitations, whereas to the processes mediated by
and there is not only a contribution from their KK towers, but also
from that of the graviton. The contributions of the towers above ,
and and above the first excitation of the
graviton are included with the help of effective four-fermion Lagrangians. We
compute the cross-sections of these processes taking into account the
contributions of the Standard Model gauge bosons, of their first KK modes and
of the corresponding KK towers and discuss the impact of the interference
between them. For pp-collisions at the LHC with the center of mass energy 14
TeV we found specific changes of the distribution tails due to the interference
effects. Such a modification of distribution tails is characteristic for the
processes mediated by particles coming from extra dimensions and should always
be taken into account when looking for them.Comment: 14 pages, 12 figures, LaTeX. References added, figures added, text
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