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

Alien Registration- Loewe, Arthur J. (Topsham, Sagadahoc County)

https://digitalmaine.com/alien_docs/9362/thumbnail.jp

On the critical end point in a two-flavor linear sigma model coupled to quarks

We use the linear sigma model coupled to quarks to explore the location of the phase transition lines in the QCD phase diagram from the point of view of chiral symmetry restoration at high temperature and baryon chemical potential. We compute analytically the effective potential in the high- and low-temperature approximations up to sixth order, including the contribution of the ring diagrams to account for the plasma screening properties. We determine the model parameters, namely, the couplings and mass-parameter, from conditions valid at the first order phase transition at vanishing temperature and, using the Hagedorn limiting temperature concept applied to finite baryon density, for a critical baryochemical potential of order of the nucleon mass. We show that when using the set of parameters thus determined, the second order phase transition line (our proxy for the crossover transition) that starts at finite temperature and zero baryon chemical potential converges to the line of first order phase transitions that starts at zero temperature and finite baryon chemical potential to determine the critical end point to lie in the region 5.02<\mu_B^{\mbox{CEP}}/T_c<5.18, 0.14, where $T_c$ is the critical transition temperature at zero baryon chemical potential.Comment: 11 pages, 3 figures, discussion extended, explicit calculations included in appendices and version accepted for publication in EPJ