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  • 24.10.Cn  (5)
  • 25.40.−h  (2)
  • 13.75 Gx  (1)
Materialart
Erscheinungszeitraum
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 331 (1988), S. 439-449 
    ISSN: 1434-601X
    Schlagwort(e): 24.10.Cn ; 24.10.-i
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We derive a transport equation for the description of non-relativistic heavy-ion collisions from time-dependentG-matrix theory. The approximations introduced are investigated within a modified Lipkin model on theA-body level and by one-dimensional calculations for colliding finite fermion systems on the two-body level. Both approximations are found to hold reasonably well. The classical limit of these equations in phase space yields a transport equation of the Vlasov-Uehling-Uhlenbeck type without double counting of interactions and uniquely determines the time-dependent mean field as well as an in-medium nucleon-nucleon cross-section on the basis of the sameG-matrix.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 342 (1992), S. 161-167 
    ISSN: 1434-601X
    Schlagwort(e): 24.10.Cn ; 25.70.−z
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present a coupled set of equations for the one-body density matrix and the two-body correlation function consistent with trace relations and conservation laws which provide an extension of correlation dynamics on the two-body level. The additional interaction terms are discussed in the context of time-dependent G-matrix theory and NQCD and studied numerically by one-dimensional calculations for colliding finite fermion systems.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1434-601X
    Schlagwort(e): 25.40.−h
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The production ofK + mesons in proton-nucleus and deuteron-nucleus collisions is analyzed with respect to one-step nucleon-nucleon (NN → N ΛK +),Δ- nucleon (ΔN → N Λ K+) and two-step pion-nucleon (πN → K + Λ) production channels on the basis of experimental ground state momentum distributions and free on-shell production processes. Whereas forK + production in proton-nucleus reactions the secondary channelπN clearly dominates at subthreshold energies, meson and nucleon induced channels are of similar magnitude in deuteron-nucleus reactions. Contrary to nucleus-nucleus collisions theΔ induced reaction channels are found to be of minor importance. The experimental differentiation of the underlying microscopic reaction channels appears possible via differential proton —K + coincidence measurements as shown in detail by the microscopic simulations including proton rescattering.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 337 (1990), S. 1-10 
    ISSN: 1434-601X
    Schlagwort(e): 05.60.+w ; 11.10.Qr ; 24.10.Cn ; 25.70.-z
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We present an extension of relativistic mean-field theories within the framework of quantum correlation dynamics starting from an effective hadronic Lagrangian density with minimal coupling between baryons and mesons. When neglecting retardation for the meson fields the conventional meson-exchange picture is obtained for the baryon-baryon interaction. The resulting equations of motion for the baryonic one-body density matrix and two-body correlation spinor matrix provide a nonperturbative framework for the description of relativistic heavy-ion collisions. Adopting semiclassical limits for the Wigner transform of the one-body density matrix a covariant transport equation is derived in the limit of time-dependent Dirac-Brueckner theory. It describes the mean-field dynamics including momentum-dependent potentials as well as in-medium nucleon-nucleon collisions on the basis of the same meson fields without double counting of interactions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 337 (1990), S. 175-183 
    ISSN: 1434-601X
    Schlagwort(e): 24.10.Cn ; 25.70.−z
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The dynamical description of strongly interacting finite Fermi systems is based on coupled equations of motion for the one-body density matrixρ(11′) and the two-body correlation functionc 2(12, 1′2′) as obtained from the density-matrix hierarchy. The truncation schemes considered exceed the conventional Brueckner-Hartree-Fock scheme and also apply for nonstationary problems. In the limit of slow processes in time the equation of motion for the two-body correlation functionc 2 can be integrated in time and closed expressions can be given for the dynamical evolution ofρ(11′). When performing a Wigner transformation and adopting semiclassical limits this gives a transport equation of the Uehling-Uhlenbeck type for the one-body phase-space distributionf(x,p;t). Furthermore, in the small amplitude limit, we obtain a set of coupled equations for particle-hole (p-h),2p-2p, 2h-2h, 2p-2h, 1p-3h, 1h-3p amplitudes beyond the level of second RPA which provide a genuine basis for the description of giant resonances and their damping width.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 340 (1991), S. 51-57 
    ISSN: 1434-601X
    Schlagwort(e): 25.40.−h
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The production ofη-mesons in proton-nucleus reactions is analysed with respect to primary nucleon-nucleon (NN→NNη) and secondary pion-nucleon (πN→ηN) production processes on the basis of Hartree-Fock groundstate momentum distributions and free on-shell production processes. The folding model adopted compares well for meson production with more involved simulations based on VUU transport equations. Similar to K+ production in proton-nucleus reactions theη-mesons are primarily produced by theπN →ηN channel. However,η-mesons are absorbed in nuclei via excitation of the N* (1535) resonance which leads to strong distortions of the primordial spectra. On the other hand, the experimental mass dependence of the differential cross sections might yield information about the in-medium properties of this resonance.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 326 (1987), S. 97-106 
    ISSN: 1434-601X
    Schlagwort(e): 25.70−z ; 25.90+k ; 13.75 Gx
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Production mechanisms for subthreshold pions in nucleus-nucleus collisions are studied on a microscopic level. The non-relativistic expansion of the pseudoscalar πNN-vertex provides a basis for the construction of several two-nucleon models. These are incorporated into a dynamical description of the heavy-ion collision by boosted harmonic oscillators that adopts essential features from TDHF. The approach allows for a separate analysis of the various production processes and the influence of the collision dynamics on the total pion yield. Results are presented for the system16O +16O at laboratory energies of 40 and 80 MeV per nucleon.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 328 (1987), S. 423-429 
    ISSN: 1434-601X
    Schlagwort(e): 24.10.Cn ; 24.10.−i
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A selfconsistent quantal two-body theory as obtained from the density-matrix hierarchy is solved numerically for the first time for a one-dimensional system modelling α+ α collisions at 80 MeV/u. Various truncation schemes for the two-body correlation function are investigated in order to explore the convergence properties of the theory. We find that perturbative treatments with respect to two-body processes do not yield reliable results in the energy regime investigated and that the nuclear stopping power sensitively depends on the order of the two-body correlations considered.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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