451 research outputs found
Kaons and pions in strange quark matter
The behavior of kaons and pions in strange quark matter in weak equilibrium,
is investigated within the SU(3) Nambu-Jona-Lasinio [NJL] model. This work
focuses a region of high densities where the behavior of mesons has not been
explored in the framework of this model. It is found that above the density
where strange valence quarks appear in the medium, , a
change of behavior of different observables is observed indicating a tendency
to the restoration of flavor symmetry. In particular, the splitting between
charge multiplets, decrease and
the low energy modes with quantum numbers of , which
are excitations of the Fermi sea, are less relevant than for lower densities.Comment: 10 pages, 3 figures included; revised version, some changes in the
discussio
Interplay between chiral and axial symmetries in a SU(2) Nambu--Jona-Lasinio Model with the Polyakov loop
We consider a two flavor Polyakov--Nambu--Jona-Lasinio (PNJL) model where the
Lagrangian includes an interaction term that explicitly breaks the U
anomaly. At finite temperature, the restoration of chiral and axial symmetries,
signaled by the behavior of several observables, is investigated. We compare
the effects of two regularizations at finite temperature, one of them, that
allows high momentum quarks states, leading to the full recovery of chiral
symmetry. From the analysis of the behavior of the topological susceptibility
and of the mesonic masses of the axial partners, it is found in the SU(2) model
that, unlike the SU(3) results, the recovery of the axial symmetry is not a
consequence of the full recovery of the chiral symmetry. Thus, one needs to use
an additional idea, by means of a temperature dependence of the anomaly
coefficient, that simulates instanton suppression effects.Comment: 21 pages, 5 figures; PRD versio
in a hot and dense medium
The behavior of and in hot strange quark matter in weak
equilibrium with temperature, is investigated within the SU(3)
Nambu-Jona-Lasinio [NJL] model. Possible manifestations of restoration of
symmetries, by temperature or density, in the behavior of and
are discussed. The role played by the combined effect of temperature and
density in the nature of the phase transition and meson behavior is also
analyzed.Comment: 15 pages, 5 figures. Contribution to the Second International
Workshop on Hadron Physics, Effective Theories of Low Energy QCD, 25-29
September, 2002 (Coimbra, Portugal
Exploring the role of model parameters and regularization procedures in the thermodynamics of the PNJL model
The equation of state and the critical behavior around the critical end point
are studied in the context of the Polyakov--Nambu--Jona--Lasinio model. We
prove that a convenient choice of the model parameters is crucial to get the
correct description of isentropic trajectories. The physical relevance of the
effects of the regularization procedure is insured by the agreement with
general thermodynamic requirements. The results are compared with simple
thermodynamic expectations and lattice data.Comment: Talk given at XIII International Conference on Hadron Spectroscopy
(Hadron 2009), Tallahassee, Florida, USA, 29 Nov - 4 Dec, 200
The QCD Critical End Point in the Context of the Polyakov--Nambu--Jona-Lasinio Model
We investigate the phase diagram of the so-called
Polyakov--Nambu--Jona-Lasinio model at finite temperature and nonzero chemical
potential with three quark flavors. Chiral and deconfinement phase transitions
are discussed, and the relevant order-like parameters are analyzed. A special
attention is payed to the critical end point (CEP): the influence of the
strangeness on the location of the CEP is studied; also the strength of the
flavor-mixing interaction alters the CEP location, once when it becomes weaker
the CEP moves to low temperatures and can even disappear.Comment: Prepared for Strangeness in Quark Matter 2011, Sept. 18--24, Cracow,
Polan
How parameters and regularization affect the PNJL model phase diagram and thermodynamic quantities
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 end point. 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.Comment: 27 pages, 7 figures, 4 tables; PRD versio
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