scholarly journals Faddeev Approach to the Nucleon in the NJL model

1997 ◽  
Vol 50 (1) ◽  
pp. 123
Author(s):  
N. Ishii ◽  
H. Asami ◽  
W. Bentz ◽  
K. Yazaki
Keyword(s):  
Magnetic Moments ◽  
Effective Interaction ◽  
Mass Difference ◽  
Mean Field ◽  
Field Approximation ◽  
Coupling Constants ◽  
Mean Field Approximation ◽  
State Matrix ◽  
Njl Model ◽  
The Mean

The nucleon and the delta are described as solutions of the relativistic Faddeev equation in the NJL model. We discuss the dependence of the baryon masses on the particular form of the four-Fermi interaction Lagrangians. Using the quark–diquark wave function, we calculate some bound state matrix elements such as the axial coupling constants, magnetic moments of the nucleon, the pion-nucleon sigma term and the proton-neutron mass difference. We also try to compare two pictures of describing the baryons in the NJL model, i.e. the mean-field approximation and the relativistic Faddeev approach. As a first step, we discuss how to improve the mean-field approximation by introducing an effective interaction. We also discuss the perturbative estimate of the deformation of the `vacuum" in the Faddeev approach.

Phase Transitions and the Ising Model

2019 ◽  
pp. 423-446
Author(s):  
Robert H. Swendsen
Keyword(s):  
Phase Transitions ◽  
Ising Model ◽  
Landau Theory ◽  
Magnetic Moments ◽  
Mean Field ◽  
Higher Dimensions ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Ising Chain ◽  
The Mean

Chapter 17 presented one example of a phase transition, the van der Waals gas. This chapter provides another, the Ising model, a widely studied model of phase transitions. We first give the solution for the Ising chain (one-dimensional model), including the introduction of the transfer matrix method. Higher dimensions are treated in the Mean Field Approximation (MFA), which is also extended to Landau theory. The Ising model is deceptively simple. It can be defined in a few words, but it displays astonishingly rich behavior. It originated as a model of ferromagnetism in which the magnetic moments were localized on lattice sites and had only two allowed values.

Deformation effects on isospin mixing and isobar analogue resonance for 74−80Kr isotopes

Open Physics ◽  
2014 ◽  
Vol 12 (7) ◽  
Author(s):  
Hasan Aygör ◽  
Serdar Ünlü ◽  
Neçla Çakmak ◽  
Cevat Selam
Keyword(s):  
Effective Interaction ◽  
Mean Field ◽  
Nucleon Nucleon ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Strength Parameter ◽  
Isobaric Analogue ◽  
Analogue Resonance ◽  
Consistent Method ◽  
The Mean

AbstractPyatov’s method has been applied to investigate Fermi beta transitions in deformed 74–80Kr isotopes. This self-consistent method, which was used to study the isobar analogue states in the spherical odd-odd nuclei, has to date not been applied for the isobar analogue states in deformed nuclei. The nucleon-nucleon residual interaction has been included so that the broken isospin symmetry in the mean field approximation has been restored and the strength parameter of the effective interaction has been taken out to be a free parameter. The energies and wave functions of the isobaric analogue excitations in 74–80Rb isotopes have been obtained within the framework of the pnQRPA method. The probability of the isospin mixing in the ground states and the centroid energies of the isobar analogue resonance have been presented and the deformation effects on these quantities have been quantified.

CHIRAL LOGARITHMIC QUARK MODEL OF N AND Δ WITH AN A-TERM IN THE MEAN-FIELD APPROXIMATION

2011 ◽  
Vol 26 (02) ◽  
pp. 235-249 ◽  
Author(s):  
M. ABU-SHADY
Keyword(s):  
Quark Model ◽  
Sigma Model ◽  
Magnetic Moments ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Spontaneous Breaking ◽  
Baryon State ◽  
Field Equations ◽  
The Mean

The A-term is included in the logarithmic quark sigma model, which is based on chiral symmetry and its spontaneous breaking. We investigate the consequences of this term and its relevance to baryon properties. The field equations have been solved in the mean-field approximation for the hedgehog baryon state. We found that including the A-term in the logarithmic quark model leads to lower energies of the nucleon and delta masses and reduces the values of the sigma commutator σπN(0), proton μp(N), and neutron μn(N) of the magnetic moments. This indicates that the inclusion of the A-term improves the calculated nucleon properties in comparison with previous work and other models.

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.

scholarly journals Locating the critical end point using the linear sigma model coupled to quarks.

2018 ◽  
Vol 172 ◽  
pp. 02003
Author(s):  
Alejandro Ayala ◽  
J. A. Flores ◽  
L. A. Hernández ◽  
S. Hernández-Ortiz
Keyword(s):  
Sigma Model ◽  
Chemical Potential ◽  
Potential Temperature ◽  
Mean Field ◽  
Field Approximation ◽  
Baryon Density ◽  
Linear Sigma Model ◽  
Mean Field Approximation ◽  
End Point ◽  
The Mean

We use the linear sigma model coupled to quarks to compute the effective potential beyond the mean field approximation, including the contribution of the ring diagrams at finite temperature and baryon density. We determine the model couplings and use them to study the phase diagram in the baryon chemical potential-temperature plane and to locate the Critical End Point.

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