Relativistic mean-field model with nonlinear derivative couplings for nuclear matter and nuclei

Chen, Yanjun

doi:10.1103/physrevc.89.064306

Cited by 5 publications

(6 citation statements)

References 33 publications

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“…The rearrangement contributions (15) and (16) to the vector and scalar potentials (13) and (14), respectively, arise from the density dependence of the couplingsΓ j in the covariant derivative (3) and the effective mass operator (4) when the field equation of the nucleons is deduced with the help of the Euler-Langrange equation…”

Section: Discussionmentioning

confidence: 99%

“…In the mean-field approximation and under the symmetries of the application to spherical nuclei, the currents and densities (77), (78), (79), and (80) reduce to the forms (34) and (35) with the appropriate coupling factors g i j . Similarly, the selfenergies (82) and (83) become simple potentials (13) and (14) where only the μ = 0 component of Σ μ and j 0 = ρ v remain. The rearrangement contributions (15) and (16) are easily recognized when the functionalsΓ j of the fields are replaced by functions Γ j of the densities.…”

Section: Discussionmentioning

confidence: 99%

“…The derivation of these rearrangement contributions is given in detail in appendix A. The factors g nσ = g pσ = g nω = g pω = −g nρ = g pρ = −g nδ = g pδ = g pγ = 1 and g nγ = 0 in (13) and (14) reflect the different coupling of neutrons and protons to the meson fields. The quantities n σ , n δ , n ω , and n ρ are source densities in the field equations of the mesons.…”

Section: Lagrangian Density and Field Equationsmentioning

confidence: 99%

“…Many parametrisations [5] have been developed for different applications. The effects of other types of interaction vertices, e.g., with derivative couplings [6][7][8][9][10][11][12][13][14][15] or tensor couplings, are less intensively explored.…”

Section: Introductionmentioning

confidence: 99%

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Parametrisations of relativistic energy density functionals with tensor couplings

Typel

Terrero

2020

Eur. Phys. J. A

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The relativistic density functional with minimal density dependent nucleon-meson couplings for nuclei and nuclear matter is extended to include tensor couplings of the nucleons to the vector mesons. The dependence of the minimal couplings on either vector or scalar densities is explored. New parametrisations are obtained by a fit to nuclear observables with uncertainties that are determined self-consistently. The corresponding nuclear matter parameters at saturation are determined including their uncertainties. An improvement in the description of nuclear observables, in particular for binding energies and diffraction radii, is found when tensor couplings are considered, accompanied by an increase of the Dirac effective mass. The equations of state for symmetric nuclear matter and pure neutron matter are studied for all models. The density dependence of the nuclear symmetry energy, the Dirac effective masses and scalar densities is explored. Problems at high densities for parametrisations using a scalar density dependence of the couplings are identified due to the rearrangement contributions in the scalar self-energies that lead to vanishing Dirac effective masses.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Lagrangian Density and Field Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Parametrisations of relativistic energy density functionals with tensor couplings

Typel

Terrero

2020

Eur. Phys. J. A

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“…A softening of the EoS and maximum masses of neutron stars substantially below 2 M sol were found with different parametrizations assuming an energy dependence of the couplings but nonlinear self-couplings of the mesons or density dependent meson-nucleon couplings were not considered. Properties of finite nuclei were studied in reference [20] after adding meson self-interactions in the Lagrangian. A qualitative description similar to conventional RMF models was achieved but neutron star properties were not examined in this extended model.…”

Section: Introductionmentioning

confidence: 99%

Neutron star equations of state with optical potential constraint

Antić

Typel

2015

Nuclear Physics A

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Nuclear matter and neutron stars are studied in the framework of an extended relativistic mean-field (RMF) model with higher-order derivative and density dependent couplings of nucleons to the meson fields. The derivative couplings lead to an energy dependence of the scalar and vector self-energies of the nucleons. It can be adjusted to be consistent with experimental results for the optical potential in nuclear matter. Several parametrisations, which give identical predictions for the saturation properties of nuclear matter, are presented for different forms of the derivative coupling functions. The stellar structure of spherical, non-rotating stars is calculated for these new equations of state (EoS). A substantial softening of the EoS and a reduction of the maximum mass of neutron stars is found if the optical potential constraint is satisfied.

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Making a soft relativistic mean-field equation of state stiffer at high density

2015

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We study relativistic mean-field (RMF) models including nucleons interacting with scalar, vector and iso-vector mean fields and mean-field self-and cross-interaction terms. Usually, in such models the magnitude of the scalar field increases monotonically with the nucleon density, and the nucleon effective mass decreases. We demonstrate that the latter quantity stops decreasing and the equation of state stiffens, provided the mean-field self-interaction potential rises sharply in a narrow vicinity of the values of mean fields corresponding to nucleon densities n > ∼ n * > n0, where n0 is the nuclear saturation density. As a result the limiting neutron star mass increases. This procedure offers a simple way to stiffen the equation of state at densities above n * without altering it at densities n < ∼ n0. The developed scheme allows a neutron star application of the RMF models, which are well fitted to finite nuclei but do not fulfill the experimental constraint on the limiting neutron star mass. The exemplary application of the method to the well-known FSUGold model allows us to increase the limiting neutron star mass from 1.72 M⊙ to M ≥ 2.01 M⊙. A relativistic mean-field (RMF) model proposed and advertised in [1-3] is a convenient vehicle for construction of the equation of state (EoS) of baryon matter, which preserves causality. Various RMF models are successfully used to describe neutron stars (NS) and heavy-ion collisions, see [4][5][6]. The models prove to be also applicable to atomic nuclei, where a high precision in the description of gross properties of finite nuclei close to the valley of stability can be achieved [7,8]. An accurately calibrated parametrization of the RMF model was introduced in [9], known as the FSUgold model, which allows one to compute the ground state properties of finite nuclei and neutron rich matter.In order to describe finite nuclei well, one includes the self-and cross-interaction terms of meson fields [9][10][11] and/or nonlinear derivative couplings [12]. However these models yield a rather soft EoS and cannot describe the heavy NSs with masses of (2.01 ± 0.04)M ⊙ , where M ⊙ is the mass of the Sun, which were recently unambiguously identified experimentally [13,14]. Additional complication arises if hyperons are included in the consideration, since in their presence the EoS softens even more, cf. [15]. To reconcile the appropriate description of the properties of atomic nuclei and the NS mass constraints, one exploits density-dependent coupling constants [16]. Similarly, one could use mean-field-dependent coupling constants, cf. [17,18].In this Rapid Communication, we will demonstrate that, if the mean-field self-interaction potential rises sharply in a narrow vicinity of the values of mean fields corresponding to nucleon densities n > ∼ n * > n 0 , where n 0 is the nuclear saturation density, the nucleon effective mass saturates and the EoS stiffens. As a result the limiting NS mass may increase above the value (2.01 ± 0.04)M ⊙ . This procedure offers a simple way to stiffen ...

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Relativistic mean-field model with nonlinear derivative couplings for nuclear matter and nuclei

Cited by 5 publications

References 33 publications

Parametrisations of relativistic energy density functionals with tensor couplings

Parametrisations of relativistic energy density functionals with tensor couplings

Neutron star equations of state with optical potential constraint

Making a soft relativistic mean-field equation of state stiffer at high density

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