C. A. de Sousa

The QCD critical end point in the PNJL model

We investigate the role played by the Polyakov loop in the dynamics of the chiral phase transition in the framework of the so-called Polyakov-Nambu-Jona-Lasinio (PNJL) model in the SU(2) sector. We present the phase diagram where the inclusion of the Polyakov loop moves the critical points to higher temperatures, compared with the Nambu-Jona-Lasinio model results. The critical properties of physical observables, such as the baryon number susceptibility and the specific heat, are analyzed in the vicinity of the critical end point, with special focus on their critical exponents. The results with the PNJL model are closer to lattice results and we also recover the universal behavior of the critical exponents of both the baryon susceptibility and the specific heat.

Thermodynamics and critical behavior in the Nambu-Jona-Lasinio model of QCD

We investigate the phase diagram of strongly interacting matter as a function of temperature and baryonic density/chemical potential, within Nambu\char21{}Jona-Lasinio type models. We perform a systematic study concerning the existence, location, and properties of a critical end point/tricritical point, both in SU(2) and SU(3) versions of the model. We verify that, for

Medium effects on meson properties

{m}_{u}={m}_{d}=0

Scalar-pseudoscalar meson behavior and restoration of symmetries in SU(3) PNJL model

and up to a critical strange quark mass, there is a tricritical point, which becomes a critical end point in a world with realistic values of the current quark masses. The properties of physical observables, such as the baryon number susceptibility and the specific heat, are analyzed in the vicinity of the critical end point, with special focus on their critical exponents. The behavior of mesons in the

Kaons in a hot and flavor-asymmetric medium

T\ensuremath{-}{\ensuremath{\mu}}_{B}({\ensuremath{\rho}}_{B})

Aspects of mechanics and thermodynamics in introductory physics: an illustration in the context of friction and rolling

plane is analyzed in connection with possible signatures of partial and effective restoration of chiral symmetry.

The QCD critical end point in the SU(3) Nambu-Jona-Lasinio model

Abstract A coupled meson field is extracted from a quark system by means of a technique based on the time-dependent Hartree-Fock formalism. The model hamiltonian is of the Nambu-Jona-Lasinio type. Meson properties are studied, namely the ρππ coupling constant, the ρ decay width and the low-energy ππ scattering lengths, respectively, at zero and finite baryonic densities.

Kaon properties at finite baryonic density: a non-perturbative approach☆

The modification of mesonic observables in a hot medium is analyzed as a tool to investigate the restoration of chiral and axial symmetries in the context of the Polyakov-loop extended Nambu-Jona-Lasinio model. The results of the extended model lead to the conclusion that the effects of the Polyakov loop are fundamental for reproducing lattice findings. In particular, the partial restoration of the chiral symmetry is faster in the Polyakov-Nambu-Jona-Lasinio model than in the Nambu-Jona-Lasinio one, and it is responsible for several effects: the meson-quark coupling constants show a remarkable difference in both models, there is a faster tendency to recover the Okubo-Zweig-Iizuka rule, and finally the topological susceptibility nicely reproduces the lattice results around T/T{sub c}{approx_equal}1.0.

Effective restoration of the U{sub A}(1) symmetry with temperature and density

Abstract We investigate the behavior of kaons in a flavor-asymmetric quark medium at finite temperature, within SU(3) Nambu-Jona-Lasinio type models. The effect of the Fermi sea on kaon properties is weaker in the model which includes a vector-pseudovector interaction than in the model without it. The study of the combined effect of density and temperature on the vacuum and kaon properties shows that the low temperature regime does not change significantly the effects observed at T = 0; as the temperature increases the mass splitting between K + and K − modes, however reduced, is still meaningful.

Fermi sea effects on pion and kaon properties in the Nambu-Jona-Lasinio model

Rolling bodies with dissipation effects are generally ignored in introductory physics courses. This is another example of the old question of the separation between mechanics and thermodynamics at this level. With the aid of an example we show that, when mechanics and thermodynamics are considered together, a better understanding of the motion of the system is achieved. Resumo. Os cursos introdutorios de Fisica ignoram, em geral, efeitos dissipativos em corpos que rolam. Este e mais um exemplo do divorcio entre a Mecânica e a Termodinâmica a este nivel. Recorrendo a um exemplo mostramos que, quando a Mecânica e a Termodinâmica sao consideradas em conjunto, se obtem um melhor entendimento do movimento destes sistemas.