2,682,959 research outputs found
Static aeroelastic program
Set of programs computes geometric, mass, aerodynamic, and structural effects on fighter and transport type aircraft at subsonic and supersonic speeds
Asymptotically Static Universe
We consider a cosmology in which the final stage of the Universe is neither
accelerating nor decelerating, but approaches an asymptotic state where the
scale factor becomes a constant value. In order to achieve this, we first bring
in a scale factor with the desired property and then determine the details of
the energy contents as a result of the cosmological evolution equations. We
show that such a scenario can be realized if we introduce a generalized quintom
model which consists of a scalar field and a phantom with a {\it negative}
cosmological constant term. The standard cold dark matter with is also
introduced. This is possible basically due to the balance between the matter
and the {\it negative} cosmological constant which tend to attract and scalar
field and phantom which repel in the asymptotic region. The stability analysis
shows that this asymptotic solution is classically stable.Comment: Final version published in PR
Static-static-light-light tetraquarks in lattice QCD
I report on a lattice computation of the energy of a system of two light
quarks and two static antiquarks as a function of the separation of the static
antiquarks. In terms of hadrons such a system corresponds to a pair of B mesons
and its energy to the hadronic potential. I present selected results for
different isospin, spin and parity combinations of the individual B mesons
mainly focusing on those channels relevant to determine, whether two B mesons
may form a bound tetraquark state.Comment: 6 pages, 1 figure, talk given at "Excited QCD 2011", February 20-25
2011, Les Houches, Franc
Nonsingular static global string
A new solution for the spacetime outside the core of a U(1) static global
string has been presented which is nonsingular. This is the first example of a
nonsingular spacetime around a static global string.}}Comment: Minor corrections added. Accepted for publication in Phys.Rev.
Cylindrical symmetric, non-rotating and non-static or static black hole solutions and the naked singularities
In this work, a four-dimensional cylindrical symmetric and non-static or
static space-times in the backgrounds of anti-de Sitter (AdS) space with
perfect stiff fluid, anisotropic fluid and electromagnetic field as the
stress-energy tensor, is presented. For suitable parameter conditions in the
metric function, the solution represents non-static or static non-rotating
black hole solution. In addition, we show for various parameter conditions, the
solution represents static and/or non-static models with a naked singularity
without an event horizon.Comment: 32 pages, 4 figures, typos corrected, accepted for the publication in
European Physical Journal C. arXiv admin note: text overlap with
arXiv:1811.01707; text overlap with arXiv:gr-qc/9609065 by other author
Quasi-static hydrodynamic limits
We consider hydrodynamic limits of interacting particles systems with open
boundaries, where the exterior parameters change in a time scale slower than
the typical relaxation time scale. The limit deterministic profiles evolve
quasi-statically. These limits define rigorously the thermodynamic quasi static
transformations also for transition between non-equilibrium stationary states.
We study first the case of the symmetric simple exclusion, where duality can be
used, and then we use relative entropy methods to extend to other models like
zero range systems. Finally we consider a chain of anharmonic oscillators in
contact with a thermal Langevin bath with a temperature gradient and a slowly
varying tension applied to one end.Comment: Accepted for teh publication in Journal of Statistical Physic
Are there static texture?
We consider harmonic maps from Minkowski space into the three sphere. We are
especially interested in solutions which are asymptotically constant, i.e.
converge to the same value in all directions of spatial infinity. Physical
3-space can then be compactified and can be identified topologically (but not
metrically!) with a three sphere. Therefore, at fixed time, the winding of the
map is defined. We investigate whether static solutions with non-trivial
winding number exist. The answer which we can proof here is only partial: We
show that within a certain family of maps no static solutions with non-zero
winding number exist. We discuss the existing static solutions in our family of
maps. An extension to other maps or a proof that our family of maps is
sufficiently general remains an open problem.Comment: 12 page Latex file, 1 postscript figure, submitted to PR
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