E. N. E. van Dalen

Constraints on the high-density nuclear equation of state from the phenomenology of compact stars and heavy-ion collisions

A new scheme for testing nuclear matter equations of state (EoSs) at high densities using constraints from neutron star (NS) phenomenology and a flow data analysis of heavy-ion collisions is suggested. An acceptable EoS shall not allow the direct Urca process to occur in NSs with masses below 1.5M� , and also shall not contradict flow and kaon production data of heavy-ion collisions. Compact star constraints include the mass

Effective Nucleon Masses in Symmetric and Asymmetric Nuclear Matter

The momentum and isospin dependence of the in-medium nucleon mass are studied. Two definitions of the effective mass, i.e., the Dirac mass m*D and the nonrelativistic mass m*NR which parametrizes the energy spectrum, are compared. Both masses are determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a distinct peak around the Fermi momentum. The proton-neutron mass splitting in isospin asymmetric matter is m*D,n<m*D,p and opposite for the nonrelativistic mass, i.e., m*NR,n>m*NR,p, which is consistent with nonrelativistic approaches.

The relativistic Dirac–Brueckner approach to asymmetric nuclear matter

Abstract The properties of asymmetric nuclear matter have been investigated in a relativistic Dirac–Brueckner–Hartree–Fock framework using the Bonn A potential. The components of the self-energies are extracted by projecting on Lorentz invariant amplitudes. Furthermore, the optimal representation scheme for the T -matrix, the subtracted T -matrix representation, is applied and the results are compared to those of other representation schemes. Of course, in the limit of symmetric nuclear matter our results agree with those found in literature. The binding energy E b fulfills the quadratic dependence on the asymmetry parameter and the symmetry energy is 34 MeV at saturation density. Furthermore, a neutron–proton effective mass splitting of m n * m p * is found. In addition, results are given for the mean-field effective coupling constants.

Constraining hypernuclear density functional with Λ-hypernuclei and compact stars

Abstract We present a simultaneous calculation of heavy single-Λ hypernuclei and compact stars containing hypernuclear core within a relativistic density functional theory based on a Lagrangian which includes the hyperon octet and lightest isoscalar-isovector mesons which couple to baryons with density-dependent couplings. The corresponding density functional allows for SU(6) symmetry breaking and mixing in the isoscalar sector, whereby the departures in the σ–Λ and σ–Σ couplings away from their values implied by the SU(3) symmetric model are used to adjust the theory to the laboratory and astronomical data. We fix σ–Λ coupling using the data on the single-Λ hypernuclei and derive an upper bound on the σ–Σ from the requirement that the lower bound on the maximum mass of a compact star is 2 M ⊙ .

Momentum, density, and isospin dependence of symmetric and asymmetric nuclear matter properties

Properties of symmetric and asymmetric nuclear matter have been investigated in the relativistic Dirac-Brueckner-Hartree-Fock approach based on projection techniques using the Bonn A potential. The momentum, density, and isospin dependence of the optical potentials and nucleon effective masses are studied. It turns out that the isovector optical potential depends sensitively on density and momentum, but is almost insensitive to the isospin asymmetry. Furthermore, the Dirac mass

Dirac-Brueckner-Hartree-Fock calculations for isospin asymmetric nuclear matter based on improved approximation schemes

{m}_{D}^{*}

Properties of asymmetric nuclear matter in different approaches

and the nonrelativistic mass

Nuclear matter in the crust of neutron stars derived from realistic NN interactions

{m}_{\mathit{NR}}^{*}

Model-independent study of the Dirac structure of the nucleon-nucleon interaction

which parametrizes the energy dependence of the single particle spectrum, are both determined from relativistic Dirac-Brueckner-Hartree-Fock calculations. The nonrelativistic mass shows a characteristic peak structure at momenta slightly above the Fermi momentum

Bulk properties of nuclei and realistic NN interactions

{k}_{F}