LIGHT CLUSTERS IN NUCLEAR MATTER

2011 ◽  
Vol 20 (04) ◽  
pp. 897-901
Author(s):  
GERD RÖPKE
Keyword(s):  
Nuclear Matter ◽  
Mean Field ◽  
Heavy Ion ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Einstein Condensation ◽  
Relativistic Mean Field ◽  
Self Energy ◽  
Ion Collisions ◽  
Mott Effect

Within a quantum statistical approach, a in-medium Schrödinger equation is derived for a few-nucleon system embedded in nuclear matter. Medium modifications of the cluster quasiparticles are described by self-energy and Pauli blocking effects. Benchmarks such as the nuclear statistical equilibrium, virial expansion and the relativistic mean field approximation are considered. An interesting effect is the formation of a four- or two-nucleon quantum condensate, showing the crossover from Cooper pairing to Bose-Einstein condensation. The resulting thermodynamic properties are of interest for heavy-ion collisions and astrophysical applications. Quantum condensates and the Mott effect are also of relevance for the structure of finite nuclei, specially dilute excited states like the Hoyle state of 12 C .

scholarly journals IN-MEDIUM PROPERTIES OF KAONS IN A CHIRAL APPROACH

2008 ◽  
Vol 17 (09) ◽  
pp. 1895-1905
Author(s):  
YUE-LEI CUI ◽  
BAO-XI SUN
Keyword(s):  
Nuclear Matter ◽  
Effective Mass ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Nuclear Density ◽  
Relativistic Mean Field ◽  
Self Energy ◽  
Sigma Term ◽  
Scattering Matrix Elements

The first order self-energy corrections of the kaon in the symmetric nuclear matter are calculated from kaon-nucleon scattering matrix elements using a chiral Lagrangian within the framework of relativistic mean field approximation. It shows that the effective mass and the potential of K+ meson are identical with those of K- meson in the nuclear matter, respectively. The effective mass of the kaon in the nuclear matter decreases with the nuclear density increasing, and is not relevant to the kaon-nucleon Sigma term. The kaon-nucleus potential is positive and increases with the nuclear density. Moreover, the influence of the resonance Λ(1405) on the K--nucleus potential due to the re-scattering term is discussed. Our results indicate the K- meson could not be bound in the nuclei even if the contribution of Λ(1405) resonance is considered.

LIGHT CLUSTERS IN NUCLEAR MATTER

2010 ◽  
Vol 24 (25n26) ◽  
pp. 4993-5009
Author(s):  
GERD RÖPKE
Keyword(s):  
Surrounding Medium ◽  
Mean Field ◽  
Dense Matter ◽  
Heavy Ion ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Pauli Blocking ◽  
Self Energy ◽  
Ion Collisions ◽  
Protons And Neutrons

Nuclei in dense matter are influenced by the medium. In the cluster mean-field approximation, an effective Schrodinger equation for the A-nucleon cluster is obtained accounting for the effects of the surrounding medium, such as self-energy and Pauli blocking. Similar to the single-baryon states (free protons and neutrons), the light elements (A ≤ 4) are treated as quasiparticles. Fit formulae are given for the quasiparticle shifts as function of temperature, density, asymmetry, and momentum. Composition, quantum condensates and thermodynamic functions are considered. The relevance for nuclear structure, heavy ion collisions and supernova astrophysics is shown.

FINITE TEMPERATURE MATTER SUBJECT TO STRONG MAGNETIC FIELDS

2011 ◽  
Vol 20 (supp02) ◽  
pp. 93-99
Author(s):  
DÉBORA PERES MENEZES ◽  
SIDNEY SANTOS AVANCINI ◽  
CONSTANÇA PROVIDÊNCIA
Keyword(s):  
Magnetic Fields ◽  
Quark Matter ◽  
Finite Temperature ◽  
Mean Field ◽  
Heavy Ion ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Strong Magnetic Fields ◽  
Quark Masses ◽  
Ion Collisions

Quark matter at finite temperature and subject to strong magnetic fields is possibly present in the early stages of heavy ion collisions and in the interior of protoneutron stars. We use the mean field approximation to investigate this type of quark matter described by the Nambu–Jona-Lasinio model. The effect of the magnetic field on the effective quark masses and chemical potentials is only felt for quite strong magnetic fields, above 5 × 1018 G , with larger effects for the lower densities. Spin polarizations are more sensitive to weaker magnetic fields and are larger for lower temperatures and lower densities.

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.

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 Relativistic mean field approximation to the analysis of16O(e,e′p)15Ndata at|Q2|<~0.4 (GeV/c)2

2001 ◽  
Vol 64 (2) ◽  
Author(s):  
J. M. Udías ◽  
J. A. Caballero ◽  
E. Moya de Guerra ◽  
Javier R. Vignote ◽  
A. Escuderos
Keyword(s):  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Relativistic Mean Field
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