48 research outputs found
Deconfinement Phase Transition in Neutron Stars and \delta-Meson Field
The Maxwell and Glendenning construction scenarios of deconfinement phase
transition in neutron star matter are investigated. The hadronic phase is
described within the relativistic mean-field (RMF) theory, if also the
scalar-isovector \delta-meson field is taken into account. The strange quark
phase is described in the frame of MIT bag model, including the effect of
perturbative one-gluon exchange interactions. The influence of the \delta-meson
field on the deconfinement phase transition boundary characteristics is
discussed.Comment: 4 pages, 2 figure
Scalar-Isovector Delta-Meson in the Relativistic Mean-Field Theory and the Structure of Neutron Stars with a Quark Core
In the framework of the relativistic mean-field theory, we have considered
the equation of state of superdense nuclear matter, taking into account an
effective scalar-isovector delta-meson field. The effect of the delta-meson
field on the characteristics of a Maxwell-type quark phase transition has been
studied. The quark phase is described with the aid of the improved version of
the MIT (Massachusetts Institute of Technology) bag model, in which
interactions between the u, d, s quarks inside the bag are taken into account
in the one-gluon exchange approximation. For different values of the bag
parameter B, series of neutron star models with a quark core have been built.
Stability problems for neutron stars with an infinitesimal quark core are
discussed. An estimate is obtained for the amount of energy released in a
catastrophic transformation of a critical neutron star to a star with a
finite-size quark core.Comment: 7 pages, 2 figures, Talk given at the International Conference
RUSGRAV-13, June 23-28, 2008, PFUR, Mosco
Relativistic Mean-Field Theory Equation of State of Neutron Star Matter and a Maxwellian Phase Transition to Strange Quark Matter
The equation of state of neutron star matter is examined in terms of the
relativistic mean-field theory, including a scalar-isovector -meson
effective field. The constants of the theory are determined numerically so that
the empirically known characteristics of symmetric nuclear matter are
reproduced at the saturation density. The thermodynamic characteristics of both
asymmetric nucleonic matter and -equilibrium hadron-electron
-plasmas are studied. Assuming that the transition to strange quark matter
is an ordinary first-order phase transition described by Maxwell's rule, a
detailed study is made of the variations in the parameters of the phase
transition owing to the presence of a -meson field. The quark phase is
described using an improved version of the bag model, in which interactions
between quarks are accounted for in a one-gluon exchange approximation. The
characteristics of the phase transition are determined for various values of
the bag parameter within the range and it is shown
that including a -meson field leads to a reduction in the phase
transition pressure and in the concentrations and at
the phase transition point.Comment: 17 pages, 8 figure
Exchange bias in laterally oxidized Au/Co/Au nanopillars
Au/Co/Au nanopillars fabricated by colloidal lithography of continuous
trilayers exhibit and enhanced coercive field and the appearance of an exchange
bias field with respect to the continuous layers. This is attributed to the
lateral oxidation of the Co interlayer that appears upon disc fabrication. The
dependence of the exchange bias field on the Co nanodots size and on the
oxidation degree is analyzed and its microscopic origin clarified by means of
Monte Carlo simulations based on a model of a cylindrical dot with lateral
core/shell structure.Comment: 8 pages, 4 figures. Published in Appl. Phys. Let