3,271 research outputs found
Nuclear Matter Properties in Derivative Coupling Models Beyond Mean - Field Approximation
The structure of infinite nuclear matter is studied with two of the Zimanyi -
Moszkowski (ZM) models in the framework of a relativistic approximation which
takes into account Hartree terms and beyond and is compared with the results
which come out of the relativistic Hartree - Fock approach in the linear
Walecka model. The simple treatment applied to these models can be used in
substitution to the more complicated Dirac - Brueckner - Hartree - Fock method
to perform future calculations in finite nuclei.Comment: 11 pages including 1 table, 1 figure (available upon request
Influence of pions on the hadron-quark phase transition
In this work we present the features of the hadron-quark phase transition
diagrams in which the pions are included in the system. To construct such
diagrams we use two different models in the description of the hadronic and
quark sectors. At the quark level, we consider two distinct parametrizations of
the Polyakov-Nambu-Jona-Lasinio (PNJL) models. In the hadronic side, we use a
well known relativistic mean-field (RMF) nonlinear Walecka model. We show that
the effect of the pions on the hadron-quark phase diagrams is to move the
critical end point (CEP) of the transitions lines. Such an effect also depends
on the value of the critical temperature (T_0) in the pure gauge sector used to
parametrize the PNJL models. Here we treat the phase transitions using two
values for T_0, namely, T_0 = 270 MeV and T_0 = 190 MeV. The last value is used
to reproduce lattice QCD data for the transition temperature at zero chemical
potential.Comment: 3 pages. Proceedings of XXXV Reuni\~ao de Trabalhos sobre F\'isica
Nuclear no Brasil 201
Dynamical nature of the nuclear pseudospin and its isospin asymmetry
Pseudospin symmetry in nuclei is investigated by solving the Dirac equation
with Woods-Saxon scalar and vector radial potentials. We relate the pseudospin
interaction with a pseudospin-orbit term in a Schroedinger-like equation for
the lower component of the Dirac spinor. We show that this term gives a large
contribution to the energy splittings of pseudospin partners, so that the near
pseudospin degeneracy arises from a significant cancellation among the
different terms in that equation. This is a manifestation of the dynamical
character of this symmetry in the nucleus. We analyze the isospin dependence of
the pseudospin symmetry in a nuclear isotope chain by including a
vector-isovector potential V_rho and a Coulomb potential and conclude that
V_rho gives the main contribution to the observed pseudospin isospin asymmetry.Comment: 4 pages, 2 figures, uses World Scientific style file. Contribution
presented at the VIII International Workshop on Hadron Physics, Bento
Goncalves, RS, Brazil, April 14-19, 2002. To be published by World Scientific
in the proceedings of the "International Workshop on Hadron Physics 2002
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