8,863 research outputs found
The NJL model and strange quark matter
The stability of strange quark matter is studied within the Nambu
Jona-Lasinio model with three different parameter sets. The model Lagrangian
contains 4-fermion (with and without vector interaction) and 6-fermion terms;
the minimum energy per baryon number as a function of the strangeness fraction
of the system is compared to the masses of hyperons having the same strangeness
fraction, and coherently calculated in the same version of the model, and for
the same parameter set. The results show that in none of the different
parameter sets strangelets are stable, and in some cases a minimum in the
energy per baryon does not even exist.Comment: 8 pages, 2 figures, reference added, typos corrected, version to
appear in Europhys. Let
Baryonic masses based on the NJL model
We employ the Nambu Jona--Lasinio model to determine the vacuum pressure on
the quarks in a baryon and hence their density inside. Then we estimate the
baryonic masses by implementing the local density approximation for the mean
field quark energies obtained in a uniform and isotropic system. We obtain a
fair agreement with the experimental masses.Comment: 17 pages, 3 figures. to be published on EPJ
Lattice QCD-based equations of state at vanishing net-baryon density
We present realistic equations of state for QCD matter at vanishing
net-baryon density which embed recent lattice QCD results at high temperatures
combined with a hadron resonance gas model in the low-temperature, confined
phase. In the latter, we allow an implementation of partial chemical
equilibrium, in which particle ratios are fixed at the chemical freeze-out, so
that a description closer to the experimental situation is possible. Given the
present uncertainty in the determination of the chemical freeze-out temperature
from first-principle lattice QCD calculations, we consider different values
within the expected range. The corresponding equations of state can be applied
in the hydrodynamic modeling of relativistic heavy-ion collisions at the LHC
and at the highest RHIC beam energies. Suitable parametrizations of our results
as functions of the energy density are also provided.Comment: Updated journal version with refined EoS-parametrization. July 2014.
8 pp. 4 figs. 3 parametrization-tables and weblink Ref. [45
Quark number susceptibilities: lattice QCD versus PNJL model
Quark number susceptibilities at finite quark chemical potential are
investigated in the framework of the Polyakov-loop-extended Nambu Jona-Lasinio
(PNJL) model. A detailed comparison is performed between the available lattice
data, extrapolated using a Taylor expansion around vanishing chemical
potential, and PNJL results consistently obtained from a Taylor series
truncated at the same order. The validity of the Taylor expansion is then
examined through a comparison between the full and truncated PNJL model
calculations.Comment: 8 pages, 2 figure
- …