SIGNATURES OF ISOVECTOR COMPONENTS OF THE SCALAR σ-MESON IN NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1255-1259 ◽  
Author(s):  
EDUARDO LÜTZ ◽  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
MANFRED DILLIG
Keyword(s):  
Neutron Star ◽  
Scalar Field ◽  
Neutron Stars ◽  
Mean Field ◽  
Hadronic Matter ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Intermediate States

Based on non-crossed, crossed and correlated ππ exchanges with irreducible N, Δ intermediate states, we predict an isovector component for the σ meson. We study dense hadronic matter in a generalized relativistic mean field approach with nonlinear self-couplings of the I=0,1 components of the scalar field and compare its predictions for neutron star properties with results from different models found in the literature.

scholarly journals Constraints on Microscopic and Phenomenological Equations of State of Dense Matter from GW170817

Universe ◽  
2019 ◽  
Vol 5 (10) ◽  
pp. 204 ◽  
Author(s):  
Domenico Logoteta ◽  
Ignazio Bombaci
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Mean Field ◽  
Dense Matter ◽  
Neutron Star Matter ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Three Body ◽  
Good Agreement

We discuss the constraints on the equation of state (EOS) of neutron star matter obtained by the data analysis of the neutron star-neutron star merger in the event GW170807. To this scope, we consider two recent microscopic EOS models computed starting from two-body and three-body nuclear interactions derived using chiral perturbation theory. For comparison, we also use three representative phenomenological EOS models derived within the relativistic mean field approach. For each model, we determine the β -stable EOS and then the corresponding neutron star structure by solving the equations of hydrostatic equilibrium in general relativity. In addition, we calculate the tidal deformability parameters for the two neutron stars and discuss the results of our calculations in connection with the constraints obtained from the gravitational wave signal in GW170817. We find that the tidal deformabilities and radii for the binary’s component neutron stars in GW170817, calculated using a recent microscopic EOS model proposed by the present authors, are in very good agreement with those derived by gravitational waves data.

scholarly journals Deconfinement of nonstrange hadronic matter with nucleons and Δ baryons to quark matter in neutron stars

2019 ◽  
Vol 28 (02) ◽  
pp. 1950040 ◽  
Author(s):  
Debashree Sen ◽  
T. K. Jha
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quark Matter ◽  
Mean Field ◽  
Static Condition ◽  
Hadronic Matter ◽  
Chiral Model ◽  
Vector Coupling ◽  
Binary Neutron Star ◽  
Relativistic Mean Field

We explore the possibility of formation of [Formula: see text] baryons (1232[Formula: see text]MeV) in neutron star matter in an effective chiral model within the relativistic mean-field framework. With variation in delta-meson couplings, consistent with the constraints imposed on them, the resulting equation-of-state (EoS) is obtained and the neutron star properties are calculated for static and spherical configuration. Within the framework of our model, the critical densities of formation of [Formula: see text] and the properties of neutron stars (NS) are found to be very sensitive to the iso-vector coupling compared to the scalar or vector couplings. We revisit the [Formula: see text] puzzle and look for the possibility of phase transition from nonstrange hadronic matter (including nucleons and [Formula: see text]) to deconfined quark matter, based on QCD theories. The resultant hybrid star configurations satisfy the observational constraints on mass from the most massive pulsars PSR J1614-2230 and PSR J0348+0432 in static condition obtained with the general hydrostatic equilibrium based on GTR. Our radius estimates are well within the limits imposed from observational analysis of QLMBXs. The obtained values of [Formula: see text] are in agreement with the recent bounds specified from the observation of gravitational wave (GW170817) from binary neutron star merger. The constraint on baryonic mass from the study of binary system PSR J0737-3039 is also satisfied with our hybrid EoS.

NONLINEAR σ, δ DERIVATIVE SELF-COUPLINGS IN A RMFT FOR NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1485-1491 ◽  
Author(s):  
SÉRGIO S. ROCHA ◽  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
MANFRED DILLIG
Keyword(s):  
Neutron Stars ◽  
Nuclear Matter ◽  
Mean Field ◽  
Hadronic Matter ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Global Properties ◽  
Substantial Modification ◽  
Nonlinear Couplings

We study dense hadronic matter in a generalized relativistic mean field approach which contains nonlinear couplings of the σ, ω, ϱ, δ fields and compare its predictions for properties of neutron stars with the corresponding results from different models found in the literature. Our predictions indicate a substantial modification in static global properties of nuclear matter and neutron stars with the inclusion of the δ meson into the formalism.

SIGNATURES OF ISOVECTOR COMPONENTS OF A LIGHT SCALAR MESON IN PULSARS

2007 ◽  
Vol 16 (02n03) ◽  
pp. 373-380
Author(s):  
EDUARDO LÜTZ ◽  
MOISÉS RAZEIRA ◽  
BARDO E. J. BODMANN ◽  
CÉSAR A. ZEN VASCONCELLOS
Keyword(s):  
Neutron Star ◽  
Scalar Meson ◽  
Mean Field ◽  
Symmetry Transformation ◽  
Hadronic Matter ◽  
Meson Field ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Light Scalar ◽  
Scalar Meson Field

In a previous work, we have predicted an isovector component of the light scalar meson sector by using the chiral symmetry transformation formalism. On the basis of this result, we study dense hadronic matter in a generalized relativistic mean field approach with σ, ω and ρ mesons as well as nonlinear self-couplings of the I = 1 component of a light scalar meson field and compare its predictions for neutron star properties and with results from different models for nuclear matter found in the literature.

THE INNER CRUST OF NEUTRON STARS IN RELATIVISTIC MEAN FIELD APPROACH

2008 ◽  
Vol 17 (09) ◽  
pp. 1765-1773 ◽  
Author(s):  
JIGUANG CAO ◽  
ZHONGYU MA ◽  
NGUYEN VAN GIAI
Keyword(s):  
Boundary Conditions ◽  
Neutron Stars ◽  
Mean Field ◽  
Bcs Theory ◽  
Neutron Density ◽  
Field Approach ◽  
Hartree Fock ◽  
Relativistic Mean Field ◽  
Density Distributions ◽  
Rmf Model

The microscopic properties and superfluidity of the inner crust in neutron stars are investigated in the framework of the relativistic mean field(RMF) model and BCS theory. The Wigner-Seitz(W-S) cell of inner crust is composed of neutron-rich nuclei immersed in a sea of dilute, homogeneous neutron gas. The pairing properties of nucleons in the W-S cells are treated in BCS theory with Gogny interaction. In this work, we emphasize on the choice of the boundary conditions in the RMF approach and superfluidity of the inner crust. Three kinds of boundary conditions are suggested. The properties of the W-S cells with the three kinds of boundary conditions are investigated. The neutron density distributions in the RMF and Hartree-Fock-Bogoliubov(HFB) models are compared.

EFFECTS OF Δ-BARYON INTERACTION STRENGTH ON NEUTRON STARS PROPERTIES

2007 ◽  
Vol 16 (02n03) ◽  
pp. 175-183 ◽  
Author(s):  
J. C. T. DE OLIVEIRA ◽  
S. B. DUARTE ◽  
H. RODRIGUES ◽  
M. CHIAPPARINI ◽  
M. KYOTOKU
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Mean Field Theory ◽  
Mean Field ◽  
Interaction Strength ◽  
Hadronic Matter ◽  
Resonance Neutron ◽  
Baryon Interaction ◽  
Relativistic Mean Field ◽  
Central Regions

We investigate the effect of Δ-resonance interaction strength on the equation of state of asymmetric hadronic matter and neutron stars structure. We discuss Δ-matter formation at high densities in the context of a relativistic mean field theory. We show that the attractive nature of the Δ-baryon interaction can induce a phase transition accompanying Δ-matter formation, at values of densities presumably existing in central regions of neutron stars. The possibility of a rich Δ-resonance neutron star is presented using the proposed equation of state.

ISOVECTOR COMPONENTS OF LIGHT SCALAR MESON AND NUCLEAR MATTER PROPERTIES

2007 ◽  
Vol 16 (09) ◽  
pp. 2867-2871 ◽  
Author(s):  
C. A. Z. VASCONCELLOS ◽  
E. LÜTZ ◽  
M. RAZEIRA ◽  
B. E. J. BODMANN ◽  
M. DILLIG ◽  
...  
Keyword(s):  
Nuclear Matter ◽  
Scalar Meson ◽  
Mean Field ◽  
Symmetry Transformation ◽  
Hadronic Matter ◽  
Meson Field ◽  
Field Approach ◽  
Relativistic Mean Field ◽  
Light Scalar ◽  
Scalar Meson Field

We have predicted (contribution to this issue) an isovector component of the light scalar meson sector by using the chiral symmetry transformation formalism. On the basis of this result, we study dense hadronic matter in a generalized relativistic mean field approach with σ, ω and ρ mesons as well as nonlinear self-couplings of the I = 1 component of a light scalar meson field and compare its predictions for neutron star properties with results from different models for nuclear matter found in the literature.

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.

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