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  • 1
    Electronic Resource
    Electronic Resource
    Correlations and the Dirac structure of the nucleon self-energy (2001)
    Springer
    The European physical journal 11 (2001), S. 15-24 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 21.30.Fe Forces in hadronic systems and effective interactions – 21.65.+f Nuclear matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The Dirac structure of the nucleon self-energy in symmetric nuclear matter as well as neutron matter is derived from a realistic meson exchange model for the nucleon-nucleon (NN) interaction. It is demonstrated that the effects of correlations on the effective NN interaction in the nuclear medium can be parameterized by means of an effective meson exchange. This analysis leads to a very intuitive interpretation of correlation effects and also provides an efficient parametrization of an effective interaction to be used in relativistic structure calculations for finite nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500170092
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of the effective interaction on spectra of superfluid nuclei (1976)
    Springer
    The European physical journal 278 (1976), S. 251-255 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is attempted to improve the description of the collective 2+ and 3− states in even single closed-shell nuclei by using a “realistic” effective interaction based on the Reid soft core potential, instead of the Gaussian forces which are commonly used. As an example the Sn isotopes are considered. The results of the Reid force are not better than those of the Gaussian are. The too large excitation-energies of the collective 2+ and 3− states found earlier, apparently are not due to particular features of the Gaussian effective forces used. Explicit admixture of a quadrupole and an octupole part in the effective interaction does improve the description of the collective 2+ and 3− states, but it makes the description of the other excited states worse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409175
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  • 3
    Electronic Resource
    Electronic Resource
    Renormalized shell model matrix elements derived from nucleon-nucleon phase shifts (1978)
    Springer
    The European physical journal 284 (1978), S. 195-202 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We apply theG matrix elements calculated by Singh et al. (using the DWBA approach) to some spectra calculations forA=18, 19, 20 after first renormalizing the matrix elements by including second-order processes inG. The corrections introduced by the Distorted-Wave-Born-Correction Term are attractive for both the H.J. and Reid potentials. The magnitude and uncertainties in these corrections are discussed. Differences between these potentials are attributed chiefly to their different off-the-energy-shell behaviour. The results are compared to calculations with the Kuo matrix elements and with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411329
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  • 4
    Electronic Resource
    Electronic Resource
    Hermitian operator method calculation in thepf-shell (1978)
    Springer
    The European physical journal 286 (1978), S. 187-194 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Excitations inpf-shell nuclei that may be described by a one-body Hermitian operator are calculated. For the ground states highly correlated wave functions are used, which were obtained by means of the Generator Coordinate Method (GCM). It is found that the results of the Hermitian Operator Method (HOM) for the excited states are sometimes superior to those of the GCM, especially for the two-quasiparticle states in the N=28 nuclei50Ti,52Cr,54Fe. Typically vibrational or quasi-rotational 4+ and 6+ states in46, 48Ti,50Cr are not well reproduced by the HOM, as expected. A good account for theB(E2) values of transitions to the ground state can be given for all nuclei. It is concluded that the HOM is quite useful as a supplementary calculation and as a check for complicated calculations like the GCM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01408975
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  • 5
    Electronic Resource
    Electronic Resource
    Brueckner Random Phase approximation, a microscopic description of particle-hole states (1980)
    Springer
    The European physical journal 294 (1980), S. 87-94 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Excited states of finite nuclei are described in a selfconsistent Random Phase Approximation (RPA) starting from a realistic NN interaction like the Hamada-Johnston or Reid soft core potential. The expressions for the single particle Hamiltonian and the residual particle-hole interaction to be used in the RPA equations, are derived applying the Landau prescription to the Brueckner-Hartree-Fock (BHF) approximation for the total energy, considered as a functional of density. This Brueckner RPA is used for a description of the collective 3− and the giant multipole states in16O. The importance of the renormalisation of the p-h interaction and of the BHF selfconsistency due to rearrangement terms is investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01473124
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  • 6
    Electronic Resource
    Electronic Resource
    Orbital rearrangement in light nuclei (1972)
    Springer
    The European physical journal 253 (1972), S. 61-70 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Orbital rearrangement effects due to the removal of a proton are studied. Calculations in the nuclei16O,20Ne, and40Ca are performed using the Yale potential, and the Brink Boeker forceB1. The odd mass nuclei are not restricted to time reversal symmetry which prevents a large overestimation of the rearrangement energies. Although the orbital rearrangement energies are small (〈1.5 MeV) utilizing density independent forces one can find larger changes in the wave functions due to the rearrangement as exhibit the discussion of the quadrupole moments and the mass distributions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01387170
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  • 7
    Electronic Resource
    Electronic Resource
    Study ofpf-shell nuclei with a symmetry conserving generator coordinate method (1974)
    Springer
    The European physical journal 271 (1974), S. 377-389 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Bands based on the 0+ ground state and the first excited 0+ pairing vibrational state of48Ti,52Cr and56Fe are studied with the generator coordinate method. The generating wave functions for each value of the angular momentumJ are angular momentum and particle number projected selfconsistent Hartree-Fock-Bogoliubov states where the constrained amount of pairing correlations serves as the generator coordinate. The interaction is given by reaction matrix elements derived from the Hamada-Johnston force. The basis includes the four lowest oscillator shells. The excitation energies of the pairing vibrational states can be reproduced fairly well by the present choice of the generating wave functions, whereas the ground band is not much improved compared to projected Hartree-Bogoliubov calculations. We find that the strength of the pairing correlations in the 0+ and 2+ states of the ground state and the pairing vibrational bands can be related to data of two-particle transfer reactions. The angular momentum dependence of the pairing correlations and of the moments of inertia are studied. The results show that for a strongly paired ground state the ground state band and the pairing vibrational band intersect. This may produce in the yrast band the anomaly of the moment of inertia known from rare earth nuclei.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02126193
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  • 8
    Electronic Resource
    Electronic Resource
    Polarization effects in the Skyrme model NN interaction (1987)
    Springer
    The European physical journal 326 (1987), S. 33-39 
    Details
    ISSN: 1434-601X
    Keywords: 13.75Cs ; 11.10Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two different polarization mechanisms, relevant to the description of nucleon-nucleon (NN) interaction, are investigated within the framework of the Skyrme model. First a ‘dynamical’ polarization is considered, allowing the excitation of the interacting nucleons to theΔ resonance. This yields attractive components in the central NN interaction, in agreement with corresponding extensions of the One Boson Exchange model. Beside that, geometrical deformations of the chiral fields are considered. The calculations show the inadequacy of the semiclassical approximation and the pure Skyrme model to go beyond a 20–30% accuracy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294568
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  • 9
    Electronic Resource
    Electronic Resource
    Variational definition of the single-particle potential in the Brueckner-Hartree-Fock approach (1980)
    Springer
    The European physical journal 294 (1980), S. 95-100 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The consequences of the variational definition of the self-consistent potential in Brueckner-Hartree-Fock theory are explored to higher orders even summing up some classes of diagrams to infinity. The consistency of this definition with a diagrammatic expansion are checked. Overcounting terms in the variational approach are pointed out and their numerical influence on the ground state properties of nuclei is checked at the example of16O. Ambiguities of the potential defined by the variational procedure stemming from the property of the Pauli-operatorQ 2 =Q are studied diagrammatically and numerically. The application to16O shows that the influence of the Pauli rearrangement term is partially cancelled by the higher order starting energy rearrangement terms discussed in this work.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01473125
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  • 10
    Electronic Resource
    Electronic Resource
    The Skyrmion Skyrmion interaction and the meson exchange model for the NN potential (1986)
    Springer
    The European physical journal 325 (1986), S. 229-237 
    Details
    ISSN: 1434-601X
    Keywords: 13.75Cs ; 11.10Lm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The properties of nucleon-nucleon (NN) potentials derived from the Skyrme model are investigated compared to those of typical One-Boson-Exchange (OBE) models, For that purpose the NN as well as the nucleon-antinucleon (N¯N) potentials are evaluated for the isoscalar central channel, the isovector spin channel, and the isovector tensor channel. A comparison of NN and N¯N interactions allows a separation into terms with positive and negativeG-parity and therefore a detailed comparison with the properties of the OBE model. This analysis is performed using the classical Lagrangian of the Skyrme model and considering an extension of this Lagrangian by a term of sixth order, which has recently been proposed. The results indicate that the extended Lagrangian yields an interaction which is quite consistent with the OBE picture. The extended model, however, is much more sensitive to the values of the parameters and the approximations being used for the evaluation of the field for two baryons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289655
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