4,404 research outputs found
BPS -branes in Dual to Loop Operators
In this paper, we first compute the Killing spinors of and its certain orbifolds. Based on this, two classes of -brane
solutions are found. The first class of solutions includes -branes dual to
Wilson loops in the fundamental representation as special cases. The second
class includes the candidates of the holographic description of vortex loops in
the dual field theories.Comment: v6, typoes fixed, 14 pages, no figure
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
Deformation effect on the center-of-mass correction energy in nuclei ranging from Oxygen to Calcium
The microscopic center-of-mass (c.m.) correction energies for nuclei ranging
from Oxygen to Calcium are systematically calculated by both spherical and
axially deformed relativistic mean-field (RMF) models with the effective
interaction PK1. The microscopic c.m. correction energies strongly depend on
the isospin as well as deformation and deviate from the phenomenological ones.
The deformation effect is discussed in detail by comparing the deformed with
the spherical RMF calculation. It is found that the direct and exchange terms
of the c.m. correction energies are strongly correlated with the density
distribution of nuclei and are suppressed in the deformed case.Comment: 7 pages, 3 figures, accepted by Chin.Phys.Let
BCS-BEC crossover in nuclear matter with the relativistic Hartree-Bogoliubov theory
Based on the relativistic Hartree-Bogoliubov theory, the influence of the
pairing interaction strength on the di-neutron correlations and the crossover
from superfluidity of neutron Cooper pairs in the channel to
Bose-Einstein condensation of di-neutron pairs is systematically investigated
in the nuclear matter. The bare nucleon-nucleon interaction Bonn-B is taken in
the particle-particle channel with an effective factor to simulate the medium
effects and take into account the possible ambiguity of pairing force, and the
effective interaction PK1 is used in the particle-hole channel. If the
effective factor is larger than 1.10, a di-neutron BEC state appears in the
low-density limit, and if it is smaller than 0.85, the neutron Cooper pairs are
found totally in the weak coupling BCS region. The reference values of several
characteristic quantities which characterize the BCS-BEC crossover are obtained
respectively from the dimensionless parameter with the
scattering length and the neutron Fermi momentum, the
zero-momentum transfer density correlation function D(0) and the effective
chemical potential .Comment: 8 pages, 4 figures, 2 tables, Accepted Thursday Jun 14, 2012 for
Physical Review
Deformation effect on the center-of-mass correction energy in nuclei ranging from Oxygen to Calcium
The microscopic center-of-mass (c.m.) correction energies for nuclei ranging
from Oxygen to Calcium are systematically calculated by both spherical and
axially deformed relativistic mean-field (RMF) models with the effective
interaction PK1. The microscopic c.m. correction energies strongly depend on
the isospin as well as deformation and deviate from the phenomenological ones.
The deformation effect is discussed in detail by comparing the deformed with
the spherical RMF calculation. It is found that the direct and exchange terms
of the c.m. correction energies are strongly correlated with the density
distribution of nuclei and are suppressed in the deformed case.Comment: 7 pages, 3 figures, accepted by Chin.Phys.Let
Challenge on the Astrophysical R-process Calculation with Nuclear Mass Models
Our understanding of the rapid neutron capture nucleosynthesis process in
universe depends on the reliability of nuclear mass predictions. Initiated by
the newly developed mass table in the relativistic mean field theory (RMF), in
this paper the influence of mass models on the -process calculations is
investigated assuming the same astrophysical conditions. The different model
predictions on the so far unreachable nuclei lead to significant deviations in
the calculated r-process abundances.Comment: 3 pages, 3 figure
Neutron star properties in density-dependent relativistic Hartree-Fock theory
With the equations of state provided by the newly developed density dependent
relativistic Hartree-Fock (DDRHF) theory for hadronic matter, the properties of
the static and -equilibrium neutron stars without hyperons are studied
for the first time, and compared to the predictions of the relativistic mean
field (RMF) models and recent observational data. The influences of Fock terms
on properties of asymmetric nuclear matter at high densities are discussed in
details. Because of the significant contributions from the - and
-exchange terms to the symmetry energy, large proton fractions in
neutron stars are predicted by the DDRHF calculations, which strongly affect
the cooling process of the star. The critical mass about 1.45 , close
to the limit 1.5 determined by the modern soft X-ray data analysis,
is obtained by DDRHF with the effective interactions PKO2 and PKO3 for the
occurrence of direct Urca process in neutron stars. The maximum masses of
neutron stars given by the DDRHF calculations lie between 2.45 M and
2.49 M, which are in reasonable agreement with high pulsar mass from PSR B1516+02B. It is also found that the mass-radius
relations of neutron stars determined by DDRHF are consistent with the
observational data from thermal radiation measurement in the isolated neutron
star RX J1856, QPOs frequency limits in LMXBs 4U 0614+09 and 4U 1636-536, and
redshift determined in LMXBs EXO 0748-676.Comment: 28 pages, 11 figure
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