4,073 research outputs found
Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei
Expressing explicitly the parameters of the standard Skyrme interaction in
terms of the macroscopic properties of asymmetric nuclear matter, we show in
the Skyrme-Hartree-Fock approach that unambiguous correlations exist between
observables of finite nuclei and nuclear matter properties. We find that
existing data on neutron skin thickness of Sn isotopes give an
important constraint on the symmetry energy and its
density slope at saturation density . Combining these
constraints with those from recent analyses of isospin diffusion and double
neutron/proton ratio in heavy-ion collisions at intermediate energies leads to
a more stringent limit on approximately independent of . The implication of these new constraints on the of
Pb as well as the core-crust transition density and pressure in neutron
stars is discussed.Comment: 18 pages, 9 figures, 1 table. Significantly expanded to include a
number of details and discussions. Title shortened. Accepted version to
appear in PR
Contributions of hyperon-hyperon scattering to subthreshold cascade production in heavy ion collisions
Using a gauged flavor SU(3)-invariant hadronic Lagrangian, we calculate the
cross sections for the strangeness-exchange reactions YY to N\Xi (Y=\Lambda,
\Sigma) in the Born approximation. These cross sections are then used in the
Relativistic Vlasov-Uehling-Uhlenbeck (RVUU) transport model to study \Xi
production in Ar+KCl collisions at incident energy of 1.76A GeV and impact
parameter b=3.5 fm. We find that including the contributions of hyperon-hyperon
scattering channels strongly enhances the yield of \Xi, leading to the
abundance ratio \Xi^{-}/(\Lambda+\Sigma^{0})=3.38E-3, which is essentially
consistent with the recently measured value of by the HADES collaboration at GSI.Comment: 8 pages, 5 figure
Transition density and pressure in hot neutron stars
Using the momentum-dependent MDI effective interaction for nucleons, we have
studied the transition density and pressure at the boundary between the inner
crust and liquid core of hot neutron stars. We find that their values are
larger in neutrino-trapped neutron stars than in neutrino-free neutron stars.
Furthermore, both are found to decrease with increasing temperature of a
neutron star as well as increasing slope parameter of the nuclear symmetry
energy, except that the transition pressure in neutrino-trapped neutron stars
for the case of small symmetry energy slope parameter first increases and then
decreases with increasing temperature. We have also studied the effect of the
nuclear symmetry energy on the critical temperature above which the inner crust
in a hot neutron star disappears and found that with increasing value of the
symmetry energy slope parameter, the critical temperature decreases slightly in
neutrino-trapped neutron stars but first decreases and then increases in
neutrino-free neutron stars.Comment: 7 pages, 6 figures, version to appear in Phys. Rev.
Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions
Based on the coalescence model for light nuclei production, we show that the
yield ratio of
, d, and H in heavy-ion collisions is sensitive to the neutron relative
density fluctuation
at kinetic freeze-out. From recent experimental data in central Pb+Pb
collisions at ~GeV, ~GeV, ~GeV, ~GeV and
~GeV measured by the NA49 Collaboration at the CERN Super Proton
Synchrotron (SPS), we find a possible non-monotonic behavior of as a
function of the collision energy with a peak at ~GeV,
indicating that the density fluctuations become the largest in collisions at
this energy. With the known chemical freeze-out conditions determined from the
statistical model fit to experimental data, we obtain a chemical freeze-out
temperature of MeV and baryon chemical potential of MeV
at this collision energy, which are close to the critical endpoint in the QCD
phase diagram predicted by various theoretical studies. Our results thus
suggest the potential usefulness of the yield ratio of light nuclei in
relativistic heavy-ion collisions as a direct probe of the large density
fluctuations associated with the QCD critical phenomena.Comment: 6 pages, 1 figure, 2 tables. Correlations between neutron and proton
density fluctuations considered and presentation improved. Accepted version
to appear in PL
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