300 research outputs found
Quasi-Local Density Functional Theory and its Application within Extended Thomas-Fermi Approximation
A generalization of the Density Functional Theory is proposed. The theory
developed leads to single-particle equations of motion with a quasi-local
mean-field operator, which contains a quasi-particle position-dependent
effective mass and a spin-orbit potential. The energy density functional is
constructed using the Extended Thomas-Fermi approximation. Within the framework
of this approach the ground-state properties of the doubly magic nuclei are
considered. The calculations have been performed using the finite-range Gogny
D1S force. The results are compared with the exact Hartree-Fock calculations
Neutron Transfer Dynamics and Doorway to Fusion in Time-Dependent Hartree-Fock Theory
We analyze the details of mass exchange in the vicinity of the Coulomb
barrier for heavy-ion collisions involving neutron-rich nuclei using the
time-dependent Hartree-Fock (TDHF) theory. We discuss the time-dependence of
transfer and show that the potential barriers seen by individual
single-particle states can be considerably different than the effective barrier
for the two interacting nuclei having a single center-of-mass. For this reason
we observe a substantial transfer probability even at energies below the
effective barrier.Comment: 6 pages, 9 figure
Dualities for modal algebras from the point of view of triples
In this paper we show how the theory of monads can be used to deduce in a uniform manner several duality theorems involving categories of relations on one side and categories of algebras with homomorphisms preserving only some operations on the other. Furthermore, we investigate the monoidal structure induced by Cartesian product on the relational side and show that in some cases the corresponding operation on the algebraic side represents bimorphisms
Density dependent hadron field theory for neutron stars with antikaon condensates
We investigate and condensation in -equilibrated
hyperonic matter within a density dependent hadron field theoretical model. In
this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by
the exchange of mesons. Density dependent meson-baryon coupling constants are
obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn
A nucleon-nucleon potential. It is found that the threshold of antikaon
condensation is not only sensitive to the equation of state but also to
antikaon optical potential depth. Only for large values of antikaon optical
potential depth, condensation sets in even in the presence of negatively
charged hyperons. The threshold of condensation is always reached
after condensation. Antikaon condensation makes the equation of state
softer thus resulting in smaller maximum mass stars compared with the case
without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review
Quantum self-consistency of brane models
Continuing on our previous work, we consider a class of higher dimensional
brane models with the topology of , where
is a one-parameter compact manifold and two branes of codimension 1 are located
at the orbifold fixed points. We consider a set-up where such a solution arises
from Einstein-Yang-Mills theory and evaluate the one-loop effective potential
induced by gauge fields and by a generic bulk scalar field. We show that this
type of brane models resolves the gauge hierarchy between the Planck and
electroweak scales through redshift effects due to the warp factor . The value of is then fixed by minimizing the effective potential. We
find that, as in the Randall Sundrum case, the gauge field contribution to the
effective potential stabilises the hierarchy without fine-tuning as long as the
laplacian on has a zero eigenvalue. Scalar fields can
stabilise the hierarchy depending on the mass and the non-minimal coupling. We
also address the quantum self-consistency of the solution, showing that the
classical brane solution is not spoiled by quantum effects.Comment: 10 page
Color superconducting quark matter core in the third family of compact stars
We investigate first order phase transitions from -equilibrated
hadronic matter to color flavor locked quark matter in compact star interior.
The hadronic phase including hyperons and Bose-Einstein condensate of
mesons is described by the relativistic field theoretical model with density
dependent meson-baryon couplings. The early appearance of hyperons and/or
Bose-Einstein condensate of mesons delays the onset of phase transition
to higher density. In the presence of hyperons and/or condensate, the
overall equations of state become softer resulting in smaller maximum masses
than the cases without hyperons and condensate. We find that the maximum
mass neutron stars may contain a mixed phase core of hyperons, condensate
and color superconducting quark matter. Depending on the parameter space, we
also observe that there is a stable branch of superdense stars called the third
family branch beyond the neutron star branch. Compact stars in the third family
branch may contain pure color superconducting core and have radii smaller than
those of the neutron star branch. Our results are compared with the recent
observations on RX J185635-3754 and the recently measured mass-radius
relationship by X-ray Multi Mirror-Newton Observatory.Comment: 24 pages, RevTex, 9 figures included; section II shortened, section
III elaborated, two new curves in Fig. 9 and acknowledgements added; version
to bepublished in Phys. Rev.
Images of Betelgeuse with VLTI/MATISSE across the Great Dimming
From Nov. 2019 to May 2020, the red supergiant star Betelgeuse experienced an unprecedented drop of brightness in the visible domain called the Great Dimming event (GDE). Large atmospheric dust clouds and large photospheric convective features are suspected to be responsible for it. To better understand the dimming event, we used mid-infrared long-baseline spectro-interferometric measurements of Betelgeuse taken with the Very Large Telescope Interferometer/Multi AperTure mid-Infrared SpectroScopic Experiment (VLTI/MATISSE) instrument before (Dec. 2018), during (Feb. 2020), and after (Dec. 2020) the GDE. We present data in the 3.98-4.15 µm range to cover SiO spectral features molecules as well as adjacent continuum. We have employed geometrical models, image reconstruction, as well as radiative transfer models to monitor the spatial distribution of SiO over the stellar surface. We find a strongly inhomogeneous spatial distribution of SiO that appears to be looking very different between our observing epochs, indicative of a vigorous activity in the stellar atmosphere. The contrast of our images is small in the pseudo-continuum for all epochs, implying that our MATISSE observations support both cold spot and dust cloud model
Translationally invariant calculations of form factors, nucleon densities and momentum distributions for finite nuclei with short-range correlations included
Relying upon our previous treatment of the density matrices for nuclei (in
general, nonrelativistic self-bound finite systems) we are studying a combined
effect of center-of-mass motion and short-range nucleon-nucleon correlations on
the nucleon density and momentum distributions in light nuclei ( and
). Their intrinsic ground-state wave functions are constructed in the
so-called fixed center-of-mass approximation, starting with mean-field Slater
determinants modified by some correlator (e.g., after Jastrow or Villars). We
develop the formalism based upon the Cartesian or boson representation, in
which the coordinate and momentum operators are linear combinations of the
creation and annihilation operators for oscillatory quanta in the three
different space directions, and get the own "Tassie-Barker" factors for each
distribution and point out other model-independent results. After this
separation of the center-of-mass motion effects we propose additional analytic
means in order to simplify the subsequent calculations (e.g., within the
Jastrow approach or the unitary correlation operator method). The charge form
factors, densities and momentum distributions of and
evaluated by using the well known cluster expansions are compared with data,
our exact (numerical) results and microscopic calculations.Comment: 19 pages, 6 figure
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