2,415 research outputs found
Chemical potential as a source of stability for gravitating Skyrmions
A discussion of the stability of self gravitating Skyrmions, with a large
winding number N, in a Schwarzschild type of metric, is presented for the case
where an isospin chemical potential is introduced. It turns out that the
chemical potential stabilizes the behavior of the Skyrmion discussed previously
in the literature. This analysis is carried on in the framework of a
variational approach using different ansaetze for the radial profile of the
Skyrmion. We found a divergent behavior for the size of the Skyrmion,
associated to a certain critical value of the chemical potential. At
this point, the mass of the Skyrmion vanishes. is essentialy
independent of gravitating effects. The stability of a large N skyrmion against
decays into single particles is also discussed.Comment: 10 pages, 4 figures Small changes to the previous version and a new
referenc
Skyrmions, Hadrons and isospin chemical potential
Using the Hamiltonian formulation, in terms of collective variables, we
explore the evolution of different skyrmionic parameters as function of the
isospin chemical potential (), such as the energy density, the charge
density, the isoscalar radius and the isoscalar magnetic radius. We found that
the radii start to grow very fast for MeV, suggesting the
occurrence of a phase transition.Comment: 10 pages, 5 figure
Skyrme model and Isospin Chemical Potential
We discuss the stability of the Skyrmion solution in the presence of a finite
isospin chemical potential . Solving numerically the mass of the Skyrmion
as function of , we find a critical value MeV where the
Skyrmion mass vanishes. We compare the exact numerical treatment with an
analytical discussion based on a special shape for the profile of the Skyrmion
due to Atiyah and Manton. The extension of this ansatz for finite works
quite well for MeV. Then, for small values of , where the
analytical approach is valid, we consider the possibility of having an angular
deformation for the Skyrmionic profile, which is possible for finite values of
. This is however, a small effect. Finally we introduce finite temperature
corrections, which strength the instability induced by the chemical potential,
finding the dependence of the critical temperature on .Comment: 13 pages, 7 figure
Background field method at finite temperature and density
In this letter we make use of the Background Field Method (BFM) to compute
the effective potential of an SU(2) gauge field theory, in the presence of
chemical potential and temperature. The main idea is to consider the chemical
potential as the background field. The gauge fixing condition required by the
BFM turns out to be exactly the one we found in a previous article in a
different context.Comment: 6 pages, no figure
On the role of soft gluons in collinear parton densities
The role of soft (non-perturbative) gluons in collinear parton densities is
investigated with the Parton Branching method as a solution of the DGLAP
evolution equations. It is found that soft gluons contribute significantly to
collinear parton densities.
Within the Parton Branching frame, the Sudakov form factor can be split into
a perturbative and non-perturbative part. The non-perturbative part can be
calculated analytically under certain conditions. It is shown that the
inclusion of soft (non-perturbative) gluons to the parton density evolution is
essential for the proper cancellation of divergent terms.
It is argued that the non-perturbative part of the Sudakov form factor has
its correspondence in Transverse Momentum Dependent parton distributions.
Within the Parton Branching approach, this non-perturbative Sudakov form factor
is constrained by fits of inclusive, collinear parton densities.
We show that the non-perturbative Sudakov form factor and soft gluon
emissions are essential for inclusive distributions (collinear parton densities
and Drell-Yan transverse momentum spectra), while those soft gluons play
essentially no role in final state hadron spectra.Comment: Significantly updated including studies on parton shower and
hadronizatio
Obtaining preforms by additive fused deposition modelling (FDM) extrusion technology for the manufacture of high-performance composites
The composites industry is present in practically all industrial sectors with an annual growth rate of 5%. Its contribution to the priority "light-weighting" driver in the transport sector is key. The efficiency of the industry is made possible by the evolution of manufacturing processes that also improve the performance of the products obtained. For example, out-of-autoclave (OOA) processes can obtain high-performance composites such as those obtained by the autoclave process at lower costs. A key aspect in the development of this type of process is the preforming of continuous fibre reinforcements, which can achieve high fibre percentages while facilitating processing. Manufacturing these preforms currently requires multiple steps, equipment and tooling. TECNALIA's work developing the ADDICOMP technology, an alternative preform manufacturing method using an additive process based on Fused Deposition Modelling (FDM) is detailed in this article. This development is patented by Tecnalia and was conducted in 2 phases: (a) development of continuous fibre filaments coated with polymeric material and printable by FDM and (b) fine-tuning of FDM technology to print filaments with a very high content of continuous fibre
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