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 $\mu_c$ of the chemical potential. At this point, the mass of the Skyrmion vanishes. $\mu_c$ 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 ($\mu$), 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 $\mu \gtrsim 140$ 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 $\mu$. Solving numerically the mass of the Skyrmion as function of $\mu$, we find a critical value $\mu_c=222.8$ 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 $\mu$ works quite well for $\mu<121$ MeV. Then, for small values of $\mu$, 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 $\mu$. 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 $\mu$.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

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

Weinberg-Salam model at finite temperature and density

We present a new gauge fixing condition for the Weinberg-Salam electro-weak theory at finite temperature and density. After spontaneous symmetry breaking occurs, every unphysical term in the Lagrangian is eliminated with our gauge fixing condition. A new and simple Lagrangian can be obtained where we can identify the propagators and vertices. Some consequences are discussed, as the new gauge dependent masses of the gauge fields and the new Faddeev-Popov Lagrangian. After obtaining the quadratic terms, we calculate exactly the 1-loop effective potential identifying the contribution of every particular field.Comment: 4 pages, no figures. New references added. Typo correcte