325 research outputs found
Compositeness Effects in the Bose-Einstein Condensation
Small deviations from purely bosonic behavior of trapped atomic Bose-Einstein
condensates are investigated with the help of the quon algebra, which
interpolates between bosonic and fermionic statistics. A previously developed
formalism is employed to obtain a generalized version of the Gross-Pitaeviskii
equation. Two extreme situations are considered, the collapse of the condensate
for attractive forces and the depletion of the amount of condensed atoms with
repulsive forces. Experimental discrepancies observed in the parameters
governing the collapse and the depletion of the condensates can be accounted
for by universal fittings of the deformation parameter for each case.Comment: 17 pages, 1 tabl
The neutron star inner crust and symmetry energy
The cell structure of clusters in the inner crust of a cold \beta-equilibrium
neutron star is studied within a Thomas Fermi approach and compared with other
approaches which include shell effects. Relativistic nuclear models are
considered. We conclude that the symmetry energy slope L may have quite
dramatic effects on the cell structure if it is very large or small. Rod-like
and slab-like pasta clusters have been obtained in all models except one with a
large slope L.Comment: 16 pages, 5 figure
Light Clusters and Pasta Phases in Warm and Dense Nuclear Matter
The pasta phases are calculated for warm stellar matter in a framework of
relativistic mean-field models, including the possibility of light cluster
formation. Results from three different semiclassical approaches are compared
with a quantum statistical calculation. Light clusters are considered as
point-like particles, and their abundances are determined from the minimization
of the free energy. The couplings of the light-clusters to mesons are
determined from experimental chemical equilibrium constants and many-body
quantum statistical calculations. The effect of these light clusters on the
chemical potentials is also discussed. It is shown that including heavy
clusters, light clusters are present until larger nucleonic densities, although
with smaller mass fractions.Comment: 15 pages, 13 figures, accepted for publication in Physical review
Collective modes in relativistic npe matter at finite temperature
Isospin and density waves in neutral neutron-proton-electron (npe) matter are
studied within a relativistic mean-field hadron model at finite temperature
with the inclusion of the electromagnetic field. The dispersion relation is
calculated and the collective modes are obtained. The unstable modes are
discussed and the spinodals, which separate the stable from the unstable
regions, are shown for different values of the momentum transfer at various
temperatures. The critical temperatures are compared with the ones obtained in
a system without electrons. The largest critical temperature, 12.39 MeV, occurs
for a proton fraction y_p=0.47. For y_p=0.3 we get =5 MeV and for
y_p>0.495 MeV.
It is shown that at finite temperature the distillation effect in asymmetric
matter is not so efficient and that electron effects are particularly important
for small momentum transfers.Comment: 10 pages, 6 figure
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