Tese
Estrutura de fases da matéria de quarks quente, densa e magnetizada no modelo de Nambu–Jona-Lasinio
Autor
Duarte, Dyana Cristine
Institución
Resumen
In this thesis we make use of the NJL model to the study and description of the QCD phase
diagrams under different regimes of temperature, density and external magnetic fields. In our
first work we study the influence of the application of an external magnetic field in the diquark
condensation formation, and in the BEC-BCS crossover, in a system with two color degrees of
freedom. We have dedicated special attention to the regularization of divergent integrals, and to
the comparation with the smooth form factors scheme. We observe that the correct separation
of the magnetic contributions is crucial to the correct description of the system, without nonphysical
oscillations in the order parameters. In a second work we have studied a system with
chiral imbalance, and we have shown that a method that can extract all medium contributions
from divergent integrals before the regularization can explain why the well stablished chiral models
such as NJL fails in the description of the behavior of the critical temperature for the chiral
symmetry restoration with the increase of the chiral chemical potential m5, recently obtained by
lattice QCD simulations. Furthermore we present a way to cure the problem, using a method
that we call Medium Separation Scheme (MSS). Lastly, in our third work we came back to the
study of BEC-BCS crossover, in a more realistic model, with three colors and including the
color neutrality contidion, making use of an approximation that capture effects beyond mean
field, the Optimized Perturbation Theory (OPT). We saw that the using of OPT in the case with
neutrality require that the ratio between diquark and scalar coupling constants, Gd=Gs increase
considerably to the BEC phase exists, and consequently the BEC-BCS crossover, when comparing
with the Large Nc (or mean field) usual approximation.