A CLASS OF NONLINEAR RELATIVISTIC MODELS FOR NUCLEAR MATTER AND THE BINARY PULSAR J0737-3039A

2007 ◽  
Vol 16 (02n03) ◽  
pp. 357-363
Author(s):  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
BARDO E. J. BODMANN ◽  
DIMITER HADJIMICHEF
Keyword(s):  
Nuclear Matter ◽  
Mean Field ◽  
Gravitational Theory ◽  
Model Parameters ◽  
Static Properties ◽  
Relativistic Field ◽  
Field Approach ◽  
Star Models ◽  
Dynamical Constraints ◽  
The Moment

In this work, we calculate the moment of inertia of the pulsar of the binary system J0737-3039A in the framework of Einstein's gravitational theory combined with a relativistic field theoretical approach for nuclear matter in the slow rotating regime, taking into account that the star's frequency is much smaller than Kepler's frequency. In the description of the EoS for nuclear matter, we consider a generalized class of relativistic multi-baryon Lagrangian density mean field approach which contains adjustable nonlinear couplings of the meson fields with the baryon fields. Upon adjusting the model parameters to describe bulk static properties of ordinary nuclear matter, we determine the EoS of the pulsars. By analyzing the results, dynamical constraints for neutron star models are identified.

scholarly journals NATURALNESS IN AN EFFECTIVE FIELD THEORY FOR NEUTRON STAR MATTER

2004 ◽  
Vol 13 (07) ◽  
pp. 1413-1418 ◽  
Author(s):  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS
Keyword(s):  
Field Theory ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Effective Field Theory ◽  
Mean Field ◽  
Effective Field ◽  
Hadronic Matter ◽  
Model Parameters ◽  
Static Properties ◽  
Naive Dimensional Analysis

High density hadronic matter is studied in a generalized relativistic multi-baryon Lagrangian density mean field approach which contains nonlinear couplings of the σ, ω, ϱ fields. We compare the predictions of our model with estimates obtained within a phenomenological naive dimensional analysis based on the naturalness of the coefficients of the theory. Upon adjusting the model parameters to describe bulk static properties of ordinary nuclear matter, we show that our approach represents a natural modelling of nuclear matter under the extreme conditions of density as the ones found in the interior of neutron stars. Moreover, we show that naturalness play a major role in effective field theory and, in combination with experiment, could represent a relevant criterium to select a model among others in the description of global static properties of neutron stars.

A RELATIVISTIC MEAN FIELD THEORY FOR NUCLEAR MATTER AT T≠0

2004 ◽  
Vol 13 (07) ◽  
pp. 1177-1181
Author(s):  
ALEXANDRE MESQUITA ◽  
MOISÉS RAZEIRA ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
MANFRED DILLIG ◽  
BARDO E. J. BODMANN
Keyword(s):  
Nuclear Matter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dense Matter ◽  
Baryon Number ◽  
Coupling Constants ◽  
Model Parameters ◽  
Static Properties ◽  
Relativistic Mean Field ◽  
Protoneutron Stars

We study effects of temperature in hadron dense matter within a generalized relativistic mean field approach based on the naturalness of the various coupling constants of the theory, The Lagrangian density of our formulation contains the fundamental baryon octet, nonlinear self-couplings of the σ and δ meson fields coupled to the baryons and to the ω and ρ meson fields. By adjusting the model parameters, after inclusion in a consistent way of chemical equilibrium, baryon number and electric charge conservation, our model describes static bulk properties of ordinary nuclear matter and neutron stars. In the framework of the Sommerfeld approximation, we extend our approach to the T≠0 domain. The Sommerfeld approximation allows a drastic simplification of computational work while improving the capability of the theoretical analysis of the role of temperature on static properties of protoneutron stars. We perform the calculations by using our nonlinear model, which we extend by considering trapped neutrinos introduced into the formalism by fixing the lepton fraction. Integrating the Tolman–Oppenheimer–Volkoff equations we have obtained standard plots for the mass and radius of protoneutron stars as a function of the central density and temperature. Our predictions include the determination of an absolute value for the protoneutron star limiting mass at low and intermediate temperature regimes.

NUCLEAR MATTER WITH CONSTITUENT MESON QUANTA

1990 ◽  
Vol 05 (17) ◽  
pp. 3391-3399 ◽  
Author(s):  
AMRUTA MISHRA ◽  
H. MISHRA ◽  
S.P. MISRA
Keyword(s):  
Field Theory ◽  
Nuclear Matter ◽  
Mass Shell ◽  
Mean Field ◽  
S Wave ◽  
Field Approach ◽  
Physical Insight ◽  
The Mean

We discuss here some nonperturbative techniques of field theory, where we dress nuclear matter as a whole with off-mass-shell pions. Here s-wave pion pairs simulate the effect of σ-meson of the mean field approach of Walecka. The signatures are in agreement with earlier results along with new physical insight.

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.

NEUTRON STARS WITH PARAMETRIZED MESON COUPLINGS

2000 ◽  
Vol 15 (29) ◽  
pp. 1789-1800 ◽  
Author(s):  
A. R. TAURINES ◽  
C. A. Z. VASCONCELLOS ◽  
M. MALHEIRO ◽  
M. CHIAPPARINI
Keyword(s):  
Neutron Stars ◽  
Nuclear Matter ◽  
Degrees Of Freedom ◽  
Scalar Meson ◽  
Mean Field Theory ◽  
Mean Field ◽  
Static Properties ◽  
Relativistic Mean Field ◽  
Specific Choice

We investigate static properties of nuclear and neutron star matter by using a relativistic mean field theory with parametrized couplings. With a suitable choice of mathematical parameters, the couplings allow one to reproduce results of current quantum hadrodynamics models. For other parametrizations, a better description of bulk properties of nuclear matter is obtained. The formalism is extended to include hyperon and lepton degrees of freedom, and an analysis on the effects of the phenomenological couplings in the fermion populations and mass of neutron stars is performed. The results show a strong similarity between the predictions of ZM-like models and those with exponential couplings. We have observed in particular an extreme sensibility of the predictions of these theories on the specific choice of the values of the binding energy of nuclear matter and saturation density. Additionally, the role of the very intense scalar meson mean field found in the interior of neutron stars in the screening of the nucleon mass is discussed.

scholarly journals Spinodal instabilities in nuclear matter in a stochastic relativistic mean-field approach

2009 ◽  
Vol 80 (3) ◽  
Author(s):  
S. Ayik ◽  
O. Yilmaz ◽  
N. Er ◽  
A. Gokalp ◽  
P. Ring
Keyword(s):  
Nuclear Matter ◽  
Mean Field ◽  
Field Approach ◽  
Relativistic Mean Field
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