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Browsing by Author "Hansen, H."

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  • How parameters and regularization affect the Polyakov–Nambu–Jona-Lasinio model phase diagram and thermodynamic quantities
    Publication . Costa, P.; Hansen, H.; Ruivo, M. C.; Sousa, C. A. de
    We explore the phase diagram and the critical behavior of QCD thermodynamic quantities in the context of the so-called Polyakov-Nambu-Jona-Lasinio model. We show that this improved field theoretical model is a successful candidate for studying the equation of state and the critical behavior around the critical endpoint. We argue that a convenient choice of the model parameters is crucial to get the correct description of isentropic trajectories. The effects of the regularization procedure in several thermodynamic quantities is also analyzed. The results are compared with simple thermodynamic expectations and lattice data.
    2010-01-15Journal article Open access Show more
  • Scalar-pseudoscalar meson behavior and restoration of symmetries in SU(3) Polyakov–Nambu–Jona-Lasinio model
    Publication . Costa, P.; Ruivo, M.C.; Sousa, C. A. de; Hansen, H.; Alberico, W.M.; Costa, Pedro
    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/Tc 1.0.
    2009-06-12Journal article Open access Show more
  • The QCD critical end point in the PNJL model
    Publication . Costa, P.; Sousa, C. A. de; Ruivo, M. C.; Hansen, H.; Costa, Pedro
    We investigate the role played by the Polyakov loop in the dynamics of the chiral phase transition in the framework of the so-called 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 NJL 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.
    2009-04Journal article Open access Show more