scholarly journals ALTERNATIVE LINEAR CHIRAL MODELS FOR NUCLEAR MATTER

1999 ◽  
Vol 14 (24) ◽  
pp. 1615-1623 ◽  
Author(s):  
A. DELFINO ◽  
F. S. NAVARRA ◽  
M. NIELSEN ◽  
R. B. PRANDINI ◽  
M. CHIAPPARINI
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Saturation Properties ◽  
The Mean

The equation of state of a family of alternative linear chiral models in the mean field approximation is discussed. We investigate the analogy between some of these models and current models in the literature, and we show that it is possible to reproduce very well the saturation properties of nuclear matter.

Quartetting in Fermionic Matter and Alpha-Particle Condensation in Nuclear Systems

2006 ◽  
Vol 21 (31n33) ◽  
pp. 2513-2546 ◽  
Author(s):  
G. Röpke ◽  
P. Schuck
Keyword(s):  
Nuclear Matter ◽  
Cluster Formation ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Density Region ◽  
Nuclear Matter Density ◽  
Nuclear Systems ◽  
The Mean ◽  
Finite Nuclei

Quantum condensates in nuclear matter are treated beyond the mean-field approximation, with the inclusion of cluster formation. The occurrence of a separate binding pole in the four-particle propagator in nuclear matter is investigated with respect to the formation of a condensate of α-like particles (quartetting), which is dependent on temperature and density. Due to Pauli blocking, the formation of an α-like condensate is limited to the low-density region. Consequences for finite nuclei are considered. In particular, excitations of self-conjugate 2n-Z–2n-N nuclei near the n-α-breakup threshold are candidates for quartetting. We review some results and discuss their consequences. Exploratory calculations are performed for the density dependence of the α condensate fraction at zero temperature to address the suppression of the four-particle condensate below nuclear-matter density.

scholarly journals ρ-MESON SPECTRAL FUNCTION IN HOT NUCLEAR MATTER

2012 ◽  
Vol 21 (06) ◽  
pp. 1250063 ◽  
Author(s):  
P. C. RAJE BHAGEERATHI
Keyword(s):  
Nuclear Matter ◽  
Spectral Function ◽  
Strong Dependence ◽  
Mean Field ◽  
Field Approximation ◽  
Mass Region ◽  
Mean Field Approximation ◽  
Qhd Model ◽  
The Mean ◽  
Second Peak

The ρ-meson spectral function in hot nuclear matter is studied by taking into account the pion and the nucleon loops within the quantum hadrodynamics (QHD) model as well as using an effective chiral SU(3) model. The effects of density and temperature on the spectral function of the ρ-meson are studied assuming the ρ-meson to be with a finite momentum. These investigations are performed using both the mean field approximation (MFA) and the relativistic Hartree (RHA) approximation. The inclusion of the nucleon loop is observed to considerably change the ρ-meson spectral function. Due to a larger mass drop of ρ-meson in the RHA, it is seen that the spectral function shifts towards the low invariant mass region, whereas in the MFA the spectral function is seen to be almost centered around the nominal ρ-pole, but develops a second peak due to the opening of the Nh-channel. Within both the Walecka and the chiral SU(3) models, it is observed that the ρ-meson spectral function has a strong dependence on the nucleon-ρ meson tensor coupling.

KAON CONDENSATION AND THE NUCLEAR EQUATION OF STATE

2011 ◽  
Vol 20 (supp02) ◽  
pp. 140-145
Author(s):  
ROSANA O. GOMES ◽  
DIMITER HADJIMICHEF ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
ALEXANDRE MESQUITA ◽  
MOISÉS RAZEIRA ◽  
...  
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Degrees Of Freedom ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Charge Neutrality ◽  
Nuclear Equation Of State ◽  
Kaon Condensation ◽  
The Mean

We study the effects of phase transition in the equation of state of a neutron star containing a condensate of anti-kaons, using an effective model with derivative couplings. In our formalism, nucleons interact through the exchange of σ, ω, ϱ, and δ meson fields in the presence of electrons and muons to accomplish electric charge neutrality and beta equilibrium. The phase transition to the anti-kaons condensate was implemented through the Gibbs conditions combined with the mean-field approximation, giving rise to a mixed phase of coexistence between hadron matter and the condensed of anti-kaons. In conclusion, we have found that isovector meson degrees of freedom contribute to tighten the Equation of State of Neutron Stars.

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.

scholarly journals The Combined Effect of Rotation and Magnetic Field on Finite-Amplitude Thermal Convection

1973 ◽  
Vol 26 (5) ◽  
pp. 617 ◽  
Author(s):  
R Van der Borght ◽  
JO Murphy
Keyword(s):  
Magnetic Field ◽  
Mean Field ◽  
Field Approximation ◽  
Finite Amplitude ◽  
Combined Effect ◽  
Mean Field Approximation ◽  
Free Boundaries ◽  
Wide Range ◽  
The Mean ◽  
Basic Equations

The combined effect of an imposed rotation and magnetic field on convective transfer in a horizontal Boussinesq layer of fluid heated from below is studied in the mean field approximation. The basic equations are derived by a variational technique and their solutions are then found over a wide range of conditions, in the case of free boundaries, by numerical and analytic techniques, in particular by asymptotic and perturbation methods. The results obtained by the different techniques are shown to be in excellent agreement. As for the linear theory, the calculations predict that the simultaneous presence' of a magnetic field and rotation may produce conflicting tendencies.

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