Determination of the Effective Lagrangian in the Relativistic Hartree-Fock Theory

Jetter, M.; Weber, Fridolin; Weigel, M. K.

doi:10.1209/0295-5075/14/7/004

Cited by 10 publications

(10 citation statements)

References 24 publications

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“…In the vast majority one prefers an EOS which is based on the standard nuclear matter parameters but with a Dirac mass of approximately 0.78 m N [6,8,15,16,26]. Only in this window [31,32] one obtains positive values for c N (or b N ≫ |c N |) and more moderate meson fields, so that the problem of negative nucleon Dirac masses is avoided. The reasons given for this choice rest on a reproduction of the effective mass (∼ 0.83 m N ) [8,36], however a closer inspection according to a more elaborate investigation by Celenza and Shakin shows that values of again 0.6 m N are more appropriate for the Dirac mass [37] (see also Ref.…”

Section: B) Comparison Of the Different Approximationsmentioning

confidence: 99%

“…The resulting meson fields are then rather large and consequently one obtains a sharp drop of the Dirac masses with increasing density. This feature is even amplified by the unavoidable occurence of negative values for [23,31,32], which causes a nonmonotonic behaviour of the effective σ-masswhich increases the attraction beyondAs long as the composition of NSM is restricted to n, p, e − , and µ − only, the EOS is sufficiently stiff to reach the necessary central pressure of the star at moderate densities (see Section III.e). However if one includes more baryons in the NSM-composition the EOS becomes considerably softer and higher densities are needed to obtain sufficient central pressure.…”

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Neutron Star Properties with Relativistic Equations of State

Huber

Weber

Weigel

et al. 1998

Int. J. Mod. Phys. E

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We study the properties of neutron stars adopting relativistic equations of state of neutron star matter, calculated in the framework of the relativistic Brueckner-Hartree-Fock approximation for electrically charge neutral neutron star matter in beta-equilibrium. For higher densities more baryons (hyperons etc.) are included by means of the relativistic Hartree-or Hartree-Fock approximation. The special features of the different approximations and compositions are discussed in detail. Besides standard neutron star properties special emphasis is put on the limiting periods of neutron stars, for which the Kepler criterion and gravitation-reaction instabilities are considered. Furthermore the cooling behaviour of neutron stars is investigated, too. For comparison we give also the outcome for some nonrelativistic equations of state. I IntroductionA necessary ingredient for solving the structure equations for (rotating) neutron stars (NS) is the equation of state (EOS) [1]. For NSs the EOS has to cover a wide range of densities ranging from super-nuclear densities (up to 5 to 10 times normal nuclear matter density) in the star's core down to the density of iron at the star's surface. At present, neither heavy-ion reactions nor NS data are capable to determine the EOS accurately, and the behaviour of high-density matter is still an open and one of the most challenging problems in modern physics, containing many ingredients from different branches of physics. The theoretical determination of the EOS over such an enormous range has therefore to rely mainly on theoretical arguments and extrapolations for which no direct experimental confirmation exists. The best one can do in such a situation is a step-by-step improvement of the available models for the EOS. Since the central density of a NS is so extreme, both the Fermi momenta and the effective nucleon mass are of the order of 500 MeV, one should prefer a relativistic description [2]- [9].Neutron star matter differs from the high density systems produced in heavy ion collisions by two essential features: a) Matter in high energy collisions is still governed by the charge symmetric nuclear force while neutron star matter (NSM) is bound by gravity. Since the repulsive Coulomb force is much stronger than the gravitational attraction, NSM is much more asymmetric than "standard" matter. b) The second essential difference is caused by the weak interaction time scale of ∼ 10 −10 s, which is small in comparison with the lifetime of the star, but large in comparison with the characteristic time scale of heavy ion reactions. For that reasons "normal" matter is subject to the constraints of isospin symmetry and strangeness conservation, but NSM has to obey the constraints of charge neutrality and generalized beta-equilibrium with no strangeness conservation. It is obvious from these considerations that NSM is an even more theoretical object than nuclear "normal" matter, with a rather complex structure [2]- [9].Due to these features one can adopt the following structure o...

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Section: B) Comparison Of the Different Approximationsmentioning

confidence: 99%

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Neutron Star Properties with Relativistic Equations of State

Huber

Weber

Weigel

et al. 1998

Int. J. Mod. Phys. E

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“…On the other hand, nuclear matter calculations within the Hartree-Fock scheme showed [6,27] that to some extend these improvements can also be reached by inclusion of the m. meson and an additional tensor coupling term to the p-nucleon interaction, but without "paying" for it by additional adjustable parameters. Therefore and because of the arguments given in the Introduction in favor of more sophisticated many-body dynamics, we extend the Lagrangian to the standard Hartree-Fock…”

Section: Quantum Correci'ionsmentioning

confidence: 99%

Relativistic Thomas-Fermi calculations of finite nuclei including quantum corrections

Von-Eiff

Weigel

1992

Phys. Rev. C

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“…The nonlinear u-w model has been widely and successfully used in nuclear matter and finite nuclei calculations (see, for instance, Refs. [3,4]) to describe ground state properties.…”

Section: Introductionmentioning

confidence: 99%