14,322 research outputs found
Evidence for Compact Dark Matter in Galactic Halos
Clumped dark matter arises naturally within the framwork of generic
cosmological dark matter models. Invoking the existence of dark matter clumps
can also solve may unexplained mysteries in astrophysics and geology or
geophysics, eg. the galactic gamma-ray halo and the periodic terrestrial flood
basalt volcanic episodes. Clumped dark matter is dynamically stable to friction
and will not heat the disk. Such clumps may have already been discovered in the
form of dwarf spheroidals, and further searches are encouraged by the results
of this paper.Comment: Revised Version, includes new relevant references, Latex File, 16
pages, no figure
Two dimensional representation of the Dirac equation in Non associative algebra
In this note a simple extension of the complex algebra to higher dimension is
proposed. Using the postulated algebra a two dimensional Dirac equation is
formulated and its solution is calculated. It is found that there is a
sub-algebra where the associative nature can be recovered
Dynamics of Charged Bulk Viscous Collapsing Cylindrical Source With Heat Flux
In this paper, we have explored the effects of dissipation on the dynamics of
charged bulk viscous collapsing cylindrical source which allows the out follow
of heat flux in the form of radiations. Misner-Sharp formulism has been
implemented to drive the dynamical equation in term of proper time and radial
derivatives. We have investigated the effects of charge and bulk viscosity on
the dynamics of collapsing cylinder. To determine the effects of radial heat
flux, we have formulated the heat transport equations in the context of
Mller-Israel-Stewart theory by assuming that thermodynamics
viscous/heat coupling coefficients can be neglected within some approximations.
In our discussion, we have introduced the viscosity by the standard
(non-casual) thermodynamics approach. The dynamical equations have been coupled
with the heat transport equation equation, the consequences of resulting
coupled heat equation have been analyzed in detail.Comment: 17 Pages, no figur
New constraints on the Pion EM form factor using Pi'(-Q^2)
We study the constraints arising on the expansion parameters c and d of the
Pion electromagnetic form factor from the inclusion of pure space-like data and
the phase of time-like data along with one space-like datum, using as input the
first derivative of the QCD polarization amplitude Pi'(-Q^2). These constraints
when combined with other analyses, provide a valuable check on a determination
of c due to Guo et al. and on our previous work where pionic contribution to
the (g-2) of the muon was used as the input. This work further illustrates the
power of analyticity techniques in form factor analysis.Comment: 8 pages latex, uses EPJA style files, contains 12 figures; replaced
with version accepted for publication in EPJA, minor typos corrected,
discussion improved, reference adde
On the Reduction of Singularly-Perturbed Linear Differential Systems
In this article, we recover singularly-perturbed linear differential systems
from their turning points and reduce the rank of the singularity in the
parameter to its minimal integer value. Our treatment is Moser-based; that is
to say it is based on the reduction criterion introduced for linear singular
differential systems by Moser. Such algorithms have proved their utility in the
symbolic resolution of the systems of linear functional equations, giving rise
to the package ISOLDE, as well as in the perturbed algebraic eigenvalue
problem. Our algorithm, implemented in the computer algebra system Maple, paves
the way for efficient symbolic resolution of singularly-perturbed linear
differential systems as well as further applications of Moser-based reduction
over bivariate (differential) fields.Comment: Keywords: Moser-based Reduction, Perturbed linear Differential
systems, turning points, Computer algebr
Magnetohydrodynamic Viscous Flow Over a Shrinking Sheet With Second Order Slip Flow Model
In this paper, we investigate the magnetohydrodynamic viscous flow with
second order slip flow model over a permeable shrinking surface. We have
obtained the closed form of exact solution of Navier-Stokes equations by using
similarity variable technique. The effects of slip, suction and magnetic
parameter have been investigated in detail. The results show that there are two
solution branches, namely lower and upper solution branch. The behavior of
velocity and shear stress profiles for different values of slip, suction and
magnetic parameters has been discussed through graphs.Comment: 13 Pages, 8 Figures. Accepted for Publication in Heat Transfer
Researc
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