5,808 research outputs found
Low density expansion and isospin dependence of nuclear energy functional: comparison between relativistic and Skyrme models
In the present work we take the non relativistic limit of relativistic models
and compare the obtained functionals with the usual Skyrme parametrization.
Relativistic models with both constant couplings and with density dependent
couplings are considered. While some models present very good results already
at the lowest order in the density, models with non-linear terms only reproduce
the energy functional if higher order terms are taken into account in the
expansion.Comment: 16 pages,6 figures,5 table
Pentaquarks in the medium in the quark-meson coupling model
We calculate the properties of the pentaquarks and in
symmetric nuclear matter using the quark meson coupling model (QMC). The
stability of the in the medium with respect to the channel
is discussed.Comment: 6 pages, 5 figures, revte
Light clusters and the pasta phase
The effects of including light clusters in nuclear matter at low densities
are investigated within four different parametrizations of relativistic models
at finite temperature. Both homogeneous and inhomogeneous matter (pasta phase)
are described for neutral nuclear matter with fixed proton fractions. We
discuss the effect of the density dependence of the symmetry energy, the
temperature and the proton fraction on the non-homogeneous matter forming the
inner crust of proto-neutron stars. It is shown that the number of nucleons in
the clusters, the cluster proton fraction and the sizes of the Wigner Seitz
cell and of the cluster are very sensitive to the density dependence of the
symmetry energy.Comment: 14 pages, 14 figures; Accepted for publication in Phys. Rev.
Kaon condensation in the quark-meson coupling model and compact stars
The properties of neutron stars constituted of a crust of hadrons and an
internal part of hadrons and kaon condensate are calculated within the
quark-meson-coupling model. We have considered stars with nucleons only in the
hadron phase and also stars with hyperons as well. The results are compared
with the ones obtained from the non-linear Walecka model for the hadronic
phase.Comment: 10 pages, 6 figure
Varying Alpha Monopoles
We study static magnetic monopoles in the context of varying alpha theories
and show that there is a group of models for which the t'Hooft-Polyakov
solution is still valid. Nevertheless, in general static magnetic monopole
solutions in varying alpha theories depart from the classical t'Hooft-Polyakov
solution with the electromagnetic energy concentrated inside the core seeding
spatial variations of the fine structure constant. We show that Equivalence
Principle constraints impose tight limits on the allowed variations of alpha
induced by magnetic monopoles which confirms the difficulty to generate
significant large-scale spatial variation of the fine structure constant found
in previous works. This is true even in the most favorable case where magnetic
monopoles are the source for these variations.Comment: 8 pages, 10 figures; Version to be published in Phys. Rev.
Warm stellar matter with neutrino trapping
The properties of hybrid stars formed by hadronic and quark matter in
beta-equilibrium at fixed entropies are described by appropriate equations of
state (EOS) in the framework of relativistic mean-field theory. In this work we
include the possibility of neutrino trapped EOS and compare the star properties
with the ones obtained after deleptonization, when neutrinos have already
diffused out. We use the nonlinear Walecka model for the hadron matter with two
different sets for the hyperon couplings and the MIT Bag and the
Nambu-Jona-Lasinio models for the quark matter. The phase transition to a
deconfined quark phase is investigated. Depending on the model and the
parameter set used, the mixed phase may or may not exist in the EOS at high
densities.
The star properties are calculated for each equation of state. The maximum
mass stellar configurations obtained within the NJL have larger masses than the
ones obtained within the Bag model. The Bag model predicts a mixed phase in the
interior of the most massive stable stars while, depending on the hyperon
couplings, the NJL model predicts a mixed phase or pure quark matter. Comparing
with neutrino free stars, the maximum allowed baryonic masses for protoneutron
stars are larger for the Bag model and
larger for the NJL model when neutrino trapping is imposed.Comment: 8 pages, 8 figures, 1 tabl
Avaliação de Cultivares de Sorgo GranĂfero para Indicação no Estado do Rio Grande do Sul - Safra 2012/13.
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