9,136 research outputs found
Halos in medium-heavy and heavy nuclei with covariant density functional theory in continuum
The covariant density functional theory with a few number of parameters has
been widely used to describe the ground-state and excited-state properties for
the nuclei all over the nuclear chart. In order to describe exotic properties
of unstable nuclei, the contribution of the continuum and its coupling with
bound states should be treated properly. In this Topical Review, the
development of the covariant density functional theory in continuum will be
introduced, including the relativistic continuum Hartree-Bogoliubov theory, the
relativistic Hartree-Fock-Bogoliubov theory in continuum, and the deformed
relativistic Hartree-Bogoliubov theory in continuum. Then the descriptions and
predictions of the neutron halo phenomena in both spherical and deformed nuclei
will be reviewed. The diffuseness of the nuclear potentials, nuclear shapes and
density distributions, and the impact of the pairing correlations on nuclear
size will be discussed.Comment: 63 pages; Topical Review, J. Phys. G (in press
Microscopic linear response calculations based on the Skyrme functional plus the pairing contribution
A self-consistent Quasiparticle-Random-Phase-Approximation (QRPA) model which
employs the canonical Hartree-Fock-Bogoliubov (HFB) basis and an energy-density
functional with a Skyrme mean field part and a density-dependent pairing, is
used to study the monopole collective excitations of spherical even-even
nuclei. The influence of the spurious state on the strength function of the
isoscalar monopole excitations is clearly assessed. We compare the effect of
different kinds of pairing forces (volume pairing, surface pairing and mixed
pairing) on the monopole excitation strength function. The energy of the
Isoscalar Giant Monopole Resonance (ISGMR), which is related to the nuclear
incompressibility , is calculated for tin isotopes and the results
are discussed.Comment: Accepted for publication in Phys. Rev.
Influence of nuclear physics inputs and astrophysical conditions on Th/U chronometer
The productions of thorium and uranium are key ingredients in -process
nucleo-cosmochronology. With the combination of improved nuclear and stellar
data, we have made detailed investigations on the -process abundance pattern
in the very metal-poor halo stars based on the classical -process approach.
It is found that the results are almost independent of specified simulations to
observed abundances. The influence from nuclear mass uncertainties on Th/U
chronometer can approach 2 Gyr. Moreover, the ages of the metal-poor stars HE
1523-0901, CS 31082-001, and BD +173248 are determined as , , and Gyr, respectively. The results can
serve as an independent check for age estimate of the universe.Comment: 20 pages, 5 figures. accepted by Phys. Rev.
Transfer Learning across Networks for Collective Classification
This paper addresses the problem of transferring useful knowledge from a
source network to predict node labels in a newly formed target network. While
existing transfer learning research has primarily focused on vector-based data,
in which the instances are assumed to be independent and identically
distributed, how to effectively transfer knowledge across different information
networks has not been well studied, mainly because networks may have their
distinct node features and link relationships between nodes. In this paper, we
propose a new transfer learning algorithm that attempts to transfer common
latent structure features across the source and target networks. The proposed
algorithm discovers these latent features by constructing label propagation
matrices in the source and target networks, and mapping them into a shared
latent feature space. The latent features capture common structure patterns
shared by two networks, and serve as domain-independent features to be
transferred between networks. Together with domain-dependent node features, we
thereafter propose an iterative classification algorithm that leverages label
correlations to predict node labels in the target network. Experiments on
real-world networks demonstrate that our proposed algorithm can successfully
achieve knowledge transfer between networks to help improve the accuracy of
classifying nodes in the target network.Comment: Published in the proceedings of IEEE ICDM 201
Octet-baryon masses in finite space
We report on a recent study of finite-volume effects on the lowest-lying
octet baryon masses using the covariant baryon chiral perturbation theory up to
next-to-leading order by analysing the latest lattice QCD results
from the NPLQCD Collaboration.Comment: 4 pages, 1 figure; parallel talk delivered by XLR at the 14th
national conference on nuclear structure, April 12nd - 16th, 2012, Huzhou,
Chin
Pairing Properties of Symmetric Nuclear Matter in Relativistic Mean Field Theory
The properties of pairing correlations in symmetric nuclear matter are
studied in the relativistic mean field (RMF) theory with the effective
interaction PK1. Considering well-known problem that the pairing gap at Fermi
surface calculated with RMF effective interactions are three times larger than
that with Gogny force, an effective factor in the particle-particle channel is
introduced. For the RMF calculation with PK1, an effective factor 0.76 give a
maximum pairing gap 3.2 MeV at Fermi momentum 0.9 fm, which are
consistent with the result with Gogny force.Comment: 14 pages, 6 figures
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