M. C. Ruivo

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.

Strong and radiative meson decays in a generalized Nambu-Jona-Lasinio model☆

Abstract We investigate strong and radiative meson decays in a generalized Nambu-Jona-Lasinio model. The one loop order calculation provides a satisfactory agreement with the data for the mesonic spectrum and for radiative decays. Higher order effects for strong decays of ϱ and K ∗ are estimated to be large. We also discuss the role of the flavour mixing determinantal interaction.

Pseudoscalar neutral mesons in hot and dense matter

Abstract The behavior of neutral pseudoscalar mesons π 0 , η and η ′ in hot and dense matter is investigated, in the framework of the three flavor Nambu–Jona-Lasinio model. Three different scenarios are considered: zero density and finite temperature, zero temperature and finite density in a flavor asymmetric medium with and without strange valence quarks, and finite temperature and density. The behavior of mesons is analyzed in connection with possible signatures of restoration of symmetries. In the high density region and at zero temperature it is found that the mass of the η ′ increases, the deviation from the mass of the η being more pronounced in matter without strange valence quarks.

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

Phase diagram and critical properties within an effective model of QCD: the Nambu-Jona-Lasinio model coupled to the Polyakov loop

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

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

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

Kaons in a hot and flavor-asymmetric medium

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☆

We investigate the phase diagram of the so-called Polyakov–Nambu–Jona-Lasinio model at finite temperature and non-zero chemical potential with three quark flavors. Chiral and deconfinement phase transitions are discussed and the relevant order-like parameters are analyzed. The results are compared with simple thermodynamic expectations and lattice data. We present the phase diagram in the (T, μB) plane, paying special attention to the critical end point: as the strength of the flavor-mixing interaction becomes weaker, the critical end point moves to low temperatures and can even disappear.