778 research outputs found
Spin- and isospin-polarized states of nuclear matter in the Dirac-Brueckner-Hartree-Fock model
Spin-polarized isospin asymmetric nuclear matter is studied within the
Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism,
we present and discuss the self-consistent single-particle potentials at
various levels of spin and isospin asymmetry. We then move to predictions of
the energy per particle, also under different conditions of isospin and spin
polarization. Comparison with the energy per particle in isospin symmetric or
asymmetric unpolarized nuclear matter shows no evidence for a phase transition
to a spin ordered state, neither ferromagnetic nor antiferromagnetic.Comment: 8 pages, 6 figure
The role of lysosomal cysteine proteinases as markers of macrophage activation and as non-specific mediators of inflammation
Unitarity potentials and neutron matter at the unitary limit
We study the equation of state of neutron matter using a family of unitarity
potentials all of which are constructed to have infinite scattering
lengths . For such system, a quantity of much interest is the ratio
where is the true ground-state energy of the system,
and is that for the non-interacting system. In the limit of
, often referred to as the unitary limit, this ratio is
expected to approach a universal constant, namely . In the
present work we calculate this ratio using a family of hard-core
square-well potentials whose can be exactly obtained, thus enabling us to
have many potentials of different ranges and strengths, all with infinite
. We have also calculated using a unitarity CDBonn potential
obtained by slightly scaling its meson parameters. The ratios given by
these different unitarity potentials are all close to each other and also
remarkably close to 0.44, suggesting that the above ratio is indifferent
to the details of the underlying interactions as long as they have infinite
scattering length. A sum-rule and scaling constraint for the renormalized
low-momentum interaction in neutron matter at the unitary limit is discussed.Comment: 7.5 pages, 7 figure
Predicting the single-proton/neutron potentials in asymmetric nuclear matter
We discuss the one-body potentials for protons and neutrons obtained from
Dirac-Brueckner-Hartree-Fock calculations of neutron-rich matter, in particular
their dependence upon the degree of proton/neutron asymmetry. The closely
related symmetry potential is compared with empirical information from the
isovector component of the nuclear optical potential.Comment: 9 pages, 6 figures. Minor revisions, added comments, reference
Reduced regulator dependence of neutron-matter predictions with chiral interactions
We calculate the energy per particle in infinite neutron matter
perturbatively using chiral N3LO two-body potentials plus N2LO three-body
forces. The cutoff dependence of the predictions is investigated by employing
chiral interactions with different regulators. We find that the inclusion of
three-nucleon forces, which are consistent with the applied two-nucleon
interaction, leads to a strongly reduced regulator dependence of the results.Comment: 7 pages, 8 figures, 1 table, to be published in Physical Review
Nucleon-Nucleon Scattering in a Three Dimensional Approach
The nucleon-nucleon (NN) t-matrix is calculated directly as function of two
vector momenta for different realistic NN potentials. To facilitate this a
formalism is developed for solving the two-nucleon Lippmann-Schwinger equation
in momentum space without employing a partial wave decomposition. The total
spin is treated in a helicity representation. Two different realistic NN
interactions, one defined in momentum space and one in coordinate space, are
presented in a form suited for this formulation. The angular and momentum
dependence of the full amplitude is studied and displayed. A partial wave
decomposition of the full amplitude it carried out to compare the presented
results with the well known phase shifts provided by those interactions.Comment: 26 pages plus 10 jpg figure
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