PROPERTIES OF NUCLEONS AND NUCLEAR MATTER IN THE QUARK–DIQUARK MODEL AND EXTENSION TO FINITE DENSITY

2003 ◽  
Vol 18 (08) ◽  
pp. 1409-1412
Author(s):  
W. BENTZ ◽  
H. MINEO ◽  
A. W. THOMAS ◽  
K. YAZAKI
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Axial Vector ◽  
Bound State ◽  
Simple Approximation ◽  
Static Properties ◽  
Diquark Model ◽  
Finite Density ◽  
Single Nucleon

We describe the nucleon as a quark-diquark bound state in a simple approximation to the full Faddeev method in the Nambu-Jona-Lasinio model. In the first part of this work, we concentrate on the role of axial vector diquark correlations for the static properties of the nucleon. In the second part, we construct an equation of state of nuclear matter based on the quark-diquark model for the single nucleon.

THE ROLE OF SELF-COUPLINGS OF SCALAR MESONS IN NEUTRON STAR MATTER

2002 ◽  
Vol 17 (21) ◽  
pp. 1335-1344 ◽  
Author(s):  
S. S. POCHA ◽  
A. R. TAURINES ◽  
C. A. Z. VASCONCELLOS ◽  
M. B. PINTO ◽  
M. DILLIG
Keyword(s):  
Neutron Star ◽  
Nuclear Matter ◽  
Degrees Of Freedom ◽  
Scalar Meson ◽  
Dense Matter ◽  
Meson Field ◽  
Static Properties ◽  
Hartree Approximation ◽  
Scalar Meson Field

The influence of nonlinear cubic and quartic self-couplings of the scalar meson field in nuclear matter is investigated. In summing the leading tadpole corrections for the Dirac-vacuum, we compare two approaches, the modified relativistic Hartree approximation, applied to the Walecka model, and the relativistic Hartree approximation, employed to the nonlinear model, respectively. These two approaches render similar expressions for the equation of state of nuclear matter up to the fifth order in the scalar meson field. We find that, by exploring the parameter dependence of the two models, they yield similar results for the bulk static properties of nuclear matter. However, increasing the baryon density the two models start to deviate significantly, such as in the predictions for the maximal mass of a neutron star or in the role of hyperon degrees of freedom in dense matter. The results indicate that with increasing density, scalar meson self-couplings beyond the fourth order seem to play a significant role.

scholarly journals THE SOLITON–SOLITON INTERACTION IN THE CHIRAL DILATON MODEL

2013 ◽  
Vol 28 (27) ◽  
pp. 1350136 ◽  
Author(s):  
VALENTINA MANTOVANI-SARTI ◽  
BYUNG-YOON PARK ◽  
VICENTE VENTO
Keyword(s):  
Nuclear Matter ◽  
Interaction Energy ◽  
Short Range ◽  
Bound State ◽  
Relative Orientation ◽  
Soliton Interaction ◽  
Special Configuration ◽  
Intermediate Distance

We study the interaction between two B = 1 states in the Chiral Dilaton Model where baryons are described as nontopological solitons arising from the interaction of chiral mesons and quarks. By using the hedgehog solution for B = 1 states we construct, via a product ansatz, three possible B = 2 configurations to analyse the role of the relative orientation of the hedgehog quills in the dynamics of the soliton–soliton interaction and investigate the behavior of these solutions in the range of long/intermediate distance. One of the solutions is quite binding due to the dynamics of the π and σ fields at intermediate distance and should be used for nuclear matter studies. Since the product ansatz break down as the two solitons get close, we explore the short range distance regime with a model that describes the interaction via a six-quark bag ansatz. We calculate the interaction energy as a function of the inter-soliton distance and show that for small separations the six quarks bag, assuming a hedgehog structure, provides a stable bound state that at large separations connects with a special configuration coming from the product ansatz.

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.

STABILITY OF NEUTRON STARS WITH LARGE AMOUNT OF STRANGENESS AND THE ROLE OF δ-MESON

2007 ◽  
Vol 16 (09) ◽  
pp. 2855-2858 ◽  
Author(s):  
M. RAZEIRA ◽  
A. MESQUITA ◽  
C. A. Z. VASCONCELLOS ◽  
B. E. J. BODMANN ◽  
M. DILLIG ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Lagrangian Density ◽  
Stability Conditions ◽  
Meson Field ◽  
Strange Quarks ◽  
Strangeness Content

We investigate the role of the strange σ*, ϕ and δ meson fields on the delineation of main properties of neutron stars using a parameterized Lagrangian density model in the effective baryon and meson sectors. We assume, strange quarks are localized within the hyperon fields, which carry the strangeness content of the model. Our main goal is to analyze stability conditions of neutron stars with large amount of strangeness per baryon. Our main result indicates the inclusion of the strange (anti-)quark containing meson field σ*, besides ϕ and δ into nuclear matter, turn the equation of state stiffer this way increasing the gravitational mass of the neutron star.

CLUSTER FORMATION AND THE NUCLEAR MATTER EQUATION OF STATE

2008 ◽  
Vol 17 (10) ◽  
pp. 2145-2149
Author(s):  
GERD RÖPKE
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Cluster Formation ◽  
Bound State ◽  
Particle Theory ◽  
Medium Effects ◽  
Pauli Blocking ◽  
Particle Properties ◽  
Self Energy ◽  
Cluster Properties

Bound state formation is considered in nuclear matter within the frame of many-particle theory. Medium effects such as self-energy and Pauli blocking will modify the single-particle properties as well as the cluster properties. Consequences for the composition, the formation of quantum condensates and the symmetry energy are given.

STABILITY OF NEUTRON STARS WITH A LARGE AMOUNT OF STRANGENESS

2007 ◽  
Vol 16 (02n03) ◽  
pp. 347-356
Author(s):  
MOISES RAZEIRA ◽  
BARDO E. J. BODMANN ◽  
CÉSAR A. ZEN VASCONCELLOS ◽  
ALEXANDRE MESQUITA
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Lagrangian Density ◽  
Stability Conditions ◽  
Strange Quarks ◽  
Strange Meson ◽  
Strangeness Content

We investigate the role of the strange σ* and ϕ meson fields on the delineation of the main properties of neutron stars using a parameterized Lagrangian density model in the effective baryon and meson sectors. We assume strange quarks are localized within the hyperon fields which carry the strangeness content of the model. Our main goal is to analyze stability conditions of neutron stars with a large amount of strangeness per baryon. Our main result indicates the inclusion of the strange meson fields σ* and ϕ into nuclear matter make the equation of state stiffer thereby increasing the gravitational mass of the neutron star.

STRUCTURE FUNCTION IN NUCLEAR MATTER IN THE NJL MODEL

2003 ◽  
Vol 18 (02n06) ◽  
pp. 384-387
Author(s):  
H. MINEO ◽  
W. BENTZ ◽  
A. W. THOMAS ◽  
N. ISHII ◽  
K. YAZAKI
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Structure Function ◽  
Nuclear Matter ◽  
Structure Functions ◽  
Simple Approximation ◽  
Nucleon Structure ◽  
Confinement Effects ◽  
Njl Model ◽  
Emc Effect

In this work we discuss the EMC effect on the nucleon structure functions in nuclear matter, using a simple approximation to the relativistic Faddeev description of the nucleon in the framework of the Nambu-Jona-Lasinio (NJL) model. We adopt a stable nuclear matter equation of state, calculated in the NJL model, which incorporates confinement effects phenomenologically so as to avoid unphysical thresholds for the decay into quarks. We will compare our results for the EMC ratio in nuclear matter in the NJL model with the parametrized fits to the experimental data.

THE ROLE OF COLLECTIVE FLOW IN HEAVY ION COLLISIONS

2007 ◽  
Vol 16 (03) ◽  
pp. 677-685
Author(s):  
HANS GEORG RITTER
Keyword(s):  
Equation Of State ◽  
Nuclear Matter ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Collective Flow ◽  
Flow Measurements ◽  
Ion Collisions

The motivation for flow measurements and the actual measurements at different energy domains are reviewed. At energies around 1 AGeV flow measurements have yielded information about the equation of state of nuclear matter. At RHIC energies partonic collectivity has been established.

STRUCTURE FUNCTIONS OF THE NUCLEON IN THE QUARK–DIQUARK MODEL AND EXTENSION TO FINITE DENSITY

2003 ◽  
Vol 18 (08) ◽  
pp. 1413-1416
Author(s):  
H. MINEO ◽  
W. BENTZ ◽  
K. YAZAKI ◽  
A. W. THOMAS
Keyword(s):  
Wave Function ◽  
Light Cone ◽  
Valence Quark ◽  
Axial Vector ◽  
Diquark Model ◽  
Finite Density ◽  
Scalar Diquark ◽  
Njl Model ◽  
Momentum Distributions ◽  
Extract Information

In this work we use a simple approximation to the relativistic Faddeev description of the nucleon in the framework of the Nambu-Jona-Lasinio (NJL) model. We discuss the flavor dependence of valence quark light-cone momentum distributions, and by comparing with the empirical informations we extract information on the strength of the axial vector diquark correlations. As an extension to finite density, we also discuss the EMC effect in nuclear matter, keeping only the scalar diquark channel in the wave function.

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