scholarly journals Chirally Improved Quark Pauli Blocking in Nuclear Matter and Applications to Quark Deconfinement in Neutron Stars

Particles ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 477-499 ◽  
Author(s):  
David Blaschke ◽  
Hovik Grigorian ◽  
Gerd Röpke
Keyword(s):  
Nuclear Matter ◽  
Equations Of State ◽  
Compact Star ◽  
Mean Field ◽  
High Mass ◽  
Pauli Blocking ◽  
Density Dependent ◽  
Relativistic Mean Field ◽  
Njl Model ◽  
Rmf Model

The relativistic mean field (RMF) model of the nuclear matter equation of state was modified by including the effect of Pauli-blocking owing to quark exchange between the baryons. Different schemes of a chiral enhancement of the quark Pauli blocking was suggested according to the adopted density dependence of the dynamical quark mass. The resulting equations of state for the pressure are compared to the RMF model DD2 with excluded volume correction. On the basis of this comparison a density-dependent nucleon volume is extracted which parameterizes the quark Pauli blocking effect in the respective scheme of chiral enhancement. The dependence on the isospin asymmetry is investigated and the corresponding density dependent nuclear symmetry energy is obtained in fair accordance with phenomenological constraints. The deconfinement phase transition is obtained by a Maxwell construction with a quark matter phase described within a higher order NJL model. Solutions for rotating and nonrotating (hybrid) compact star sequences are obtained, which show the effect of high-mass twin compact star solutions for the rotating case.

HYPERON DENSITY DEPENDENCE OF HYPERON-NUCLEON INTERACTIONS IN NEUTRON STARS

2008 ◽  
Vol 17 (09) ◽  
pp. 1720-1728
Author(s):  
L. DANG ◽  
P. YUE ◽  
L. LI ◽  
P. Z. NING
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Density Dependence ◽  
Mean Field ◽  
Density Dependent ◽  
Effective Potentials ◽  
Relativistic Mean Field ◽  
Nucleon Interactions ◽  
Dependent Factor ◽  
Rmf Model

The hyperon density dependence (YDD) of hyperon-nucleon interactions are studied in the relativistic mean field (RMF) model and their influences on the properties of neutron stars are studied. The extended RMF considered the interior quarks coordinates of hyperon and bring a hyperon density dependent factor, f(ρY), to the meson-hyperon coupling vertexes. The hyperon density dependence of YN interaction affect the properties of neutron stars only after the corresponding hyperon appears. Then, the influences of the density dependence factors are almost ignored at low densities, which are clear at high densities. The compositions and properties of neutron stars are studied with and without the YDD of YN interactions for the different Σ--nucleus effective potentials, (30, 0, -30)MeV. The calculated results indicated that the YDD of YN interaction soften the equation of state of neutron stars at high densities.

ELECTROMAGNETIC AND ISOVECTOR TERMS IN STANDARD RELATIVISTIC MEAN FIELD MODEL

2011 ◽  
Vol 20 (09) ◽  
pp. 1983-2010 ◽  
Author(s):  
A. SULAKSONO
Keyword(s):  
Nuclear Matter ◽  
Field Model ◽  
Local Density ◽  
Mean Field ◽  
Binding Energies ◽  
Particle Spectrum ◽  
Mean Field Model ◽  
Density Dependent ◽  
Relativistic Mean Field ◽  
Finite Nuclei

The effects of auxiliary contribution in forms of electromagnetic tensors and relativistic electromagnetic exchange in local density approximation as well as δ meson and isovector density-dependent nonlinear terms in standard relativistic mean field model constrained by nuclear matter stability criteria in some selected finite nuclei and nuclear matter properties are studied. It is found that in the case of finite nuclei, the electromagnetic tensors play the most dominant part compared to other auxiliary terms. Due to the presence of electromagnetic tensors, the binding energies prediction of the model can be improved quite significantly. However, these terms do not yield demanded effects for rms radii prediction. In the case of nuclear matter properties, the isovector density-dependent nonlinear term plays the most crucial role in providing predictions which are quite compatible with experimental constraints. We have also shown these auxiliary contributions are indeed unable to improve the single particle spectrum results of the model.

EFFECTS OF THE ω MESON SELF COUPLING ON THE THERMAL PROPERTIES OF ASYMMETRIC NUCLEAR MATTER

2009 ◽  
Vol 24 (11n13) ◽  
pp. 1067-1070
Author(s):  
S. WIBOWO ◽  
A. SULAKSONO
Keyword(s):  
Phase Transition ◽  
Thermal Properties ◽  
Nuclear Matter ◽  
Gas Phase ◽  
Mean Field ◽  
Binodal Curve ◽  
Asymmetric Nuclear Matter ◽  
Relativistic Mean Field ◽  
Chemical Instabilities ◽  
Rmf Model

Effects of the ω meson self coupling (OMSC) on the thermal properties of asymmetric nuclear matter (ANM) are studied within the framework of relativistic mean field (RMF) model that includes contributions of all possible mixed interactions among meson fields involved up to quartic order. In particular, we study the mechanical and chemical instabilities (spinodal), as well as the liquid-gas phase transition (binodal) at finite temperature. It is found that the onset of spinodal instabilities and the binodal curve are only marginally affected by variation of the OMSC parameter, whereas the binodal curve shows a strong correlation to the symmetry energy. Comparison with other ERMF parameter sets is also performed.

scholarly journals PHASE TRANSITION AND HYBRID STAR IN A NONLINEAR σ–ω MODEL

1999 ◽  
Vol 08 (02) ◽  
pp. 107-120 ◽  
Author(s):  
S. ACHARYA ◽  
L. MAHARANA ◽  
R. MOHANTY ◽  
P. K. PANDA
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Equations Of State ◽  
Mean Field Theory ◽  
Mean Field ◽  
Coupling Constant ◽  
Hybrid Star ◽  
Relativistic Mean Field ◽  
Outer Periphery

The phase transition between nuclear matter and quark matter is examined. The relativistic mean field theory (RMF) is considered with interacting nucleons and mesons using TM1 parameter set for the nuclear matter equations of state. It is found that the transition point depends on coupling constant αs and bag pressure. From the study of the structure of a hybrid neutron star, it is observed that the star contains quark matter in the interior and neutron matter on the outer periphery.

δ MESON EFFECTS ON ASYMMETRIC NUCLEAR MATTER

2008 ◽  
Vol 17 (09) ◽  
pp. 1815-1824 ◽  
Author(s):  
B. LIU ◽  
M. DI TORO ◽  
V. GRECO
Keyword(s):  
Neutron Stars ◽  
Nuclear Matter ◽  
Mean Field ◽  
Coupling Scheme ◽  
Asymmetric Nuclear Matter ◽  
Density Dependent ◽  
Remarkable Effect ◽  
Relativistic Mean Field ◽  
The Stability ◽  
The Impact

The impact of a δ meson field (the scalar-isovector channel) on asymmetric nuclear matter is studied within relativistic mean-field (RMF) models with both constant and density dependent (DD) nucleon-meson couplings. The Equation of State (EOS) for asymmetric nuclear matter and the neutron star properties by the different models are compared. We find that the δ-field in the constant coupling scheme leads to a larger repulsion in dense neutron-rich matter and to a definite splitting of proton and neutron effective masses, finally influencing the stability of the neutron stars. A broader analysis of possible δ-field effects is achieved considering also density dependent nucleon-meson coupling. A remarkable effect on the relation between mass and radius for the neutron stars is seen, showing a significant reduction of the radius along with a moderate mass reduction due to the increase of the effective δ coupling in high density regions.

scholarly journals Properties of rotating neutron star in density-dependent relativistic mean-field models

2020 ◽  
pp. 2150001
Author(s):  
Rashid Riahi ◽  
Seyed Zafarollah Kalantari
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quadrupole Moment ◽  
Stability Region ◽  
Equations Of State ◽  
Mean Field ◽  
Low Frequency ◽  
Density Dependent ◽  
Relativistic Mean Field ◽  
Limit Value

Equilibrium sequences were developed for rotating neutron stars in the relativistic mean-field interaction framework using four density-dependent equations of state (EOSs) for the neutron star matter. These sequences were constructed for the observed rotation frequencies of 25, 317, 346, 716 and 1122[Formula: see text]Hz. The bounds of sequences, the secular axisymmetric instability, static and Keplerian sequences were calculated in each model to determine the stability region. The gravitational mass, quadrupole moment, polar, forward and backward redshifts, and Kerr parameter were calculated according to this stability region, and the allowable range of these quantities was then determined for each model. According to the results, DDF and DD-ME[Formula: see text] were unable to properly describe the low-frequency neutron stars, PSR J0348+432, PSR J1614-2230 and PSR J0740+6620 rotate at a frequency of 25, 317 and 346[Formula: see text]Hz, respectively. On the other hand, all the selected EOSs properly described the rotation of PSR J1748-244ad and PSR J1739-285 at a frequency of 716 and 1122[Formula: see text]Hz, respectively. The mass of these stars was, therefore, in the range of [Formula: see text] and [Formula: see text], respectively. The polar, forward and backward redshifts, and the quadrupole moment were calculated in all the selected rotating frequencies and the Keplerian sequence. The results were consistent with observations. Confirming the mass of [Formula: see text] for EXO 0748-676, our result, [Formula: see text], will be close to the observed value, and the EOSs used in this study properly describe this star. Interestingly, the extremum of Kerr parameter, polar, forward and backward redshifts in all models reached constant values of, [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively. These behaviors of redshifts and Kerr parameter are approximately independent of EOS. The observed behaviors must evaluate by other EOSs to find universal relations for these quantities. Also, a limit value was found for each of these parameters. In this case where these parameters are greater than the limit value, the star can rotate at a frequency equal to or greater than [Formula: see text][Formula: see text]Hz.

scholarly journals Relativistic density functional for nuclear matter

2019 ◽  
Vol 204 ◽  
pp. 05001
Author(s):  
Stefan Gmuca ◽  
Kristian Petrík ◽  
Jozef Leja
Keyword(s):  
Energy Density ◽  
Nuclear Matter ◽  
Density Functional ◽  
Mean Field ◽  
Dense Matter ◽  
Coupling Constants ◽  
Effective Coupling ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Rmf Model

In the present work, we have mapped the exchange Fock contributions from the Dirac–Hartree–Fock (DHF) approach for nuclear matter onto the direct Hartree terms. This results in the relativistic mean field (RMF) model with the density dependent couplings. The density dependence of the effective coupling constants thus reflects the exchange correlations. The exchange part of an energy density of the linear DHF model in dense matter is evaluated in a parameter-free closed form and, after the rearrangement of the terms, expressed as density functional.

scholarly journals Nucleon properties inside the compressed nuclear matter

2018 ◽  
Vol 27 (04) ◽  
pp. 1850030
Author(s):  
Jacek Rożynek
Keyword(s):  
Energy Transfer ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Symmetry Energy ◽  
Mean Field ◽  
Equilibrium Density ◽  
Nucleon Mass ◽  
Relativistic Mean Field ◽  
Rmf Model

In this work, we show the modifications of nucleon mass and nucleon radius with the help of the extended Relativistic Mean Field (RMF) model. We argue that even small departures above nuclear equilibrium density with constant nucleon mass require an energy transfer from the repulsive mean field to the quarks forming nucleon massive bags in Nuclear Matter (NM), together with the decrease in the nucleon volume. The transfer, which is proportional to pressure and absent in a standard RMF approach, provides good values for nuclear compressibility, symmetry energy and its slope. Different courses of the Equation of State (EOS), which depend on the energy transfer, are considered.

scholarly journals Relativistic Mean-Field Approximation with Density-Dependent Screening Meson Masses in Nuclear Matter

2003 ◽  
Vol 12 (04) ◽  
pp. 543-554 ◽  
Author(s):  
Bao-Xi Sun ◽  
Xiao-Fu Lu ◽  
Peng-Nian Shen ◽  
En-Guang Zhao
Keyword(s):  
Nuclear Matter ◽  
Field Model ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Mean Field Model ◽  
Density Dependent ◽  
Relativistic Mean Field ◽  
Saturation Properties ◽  
The Masses

The Debye screening masses of the σ, ω and neutral ρ mesons and the photon are calculated in the relativistic mean-field approximation. As the density of the nucleon increases, all the screening masses of mesons increase. A different result with Brown–Rho scaling is shown, which implies a reduction in the mass of all the mesons in the nuclear matter, except the pion. Replacing the masses of the mesons with their corresponding screening masses in the Walecka-1 model, five saturation properties of the nuclear matter are fixed reasonably, and then a density-dependent relativistic mean-field model is proposed without introducing the nonlinear self-coupling terms of mesons.

Sign in / Sign up

Export Citation Format

Share Document