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  • 1
    Electronic Resource
    Electronic Resource
    The question of a “best” lower bound in variational calculations (1968)
    Springer
    The European physical journal 210 (1968), S. 309-311 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Information on the spectral representation of a trial wave function is used to improve the lower bound to the smallest eigenvalue of a quantum mechanical system, given by the formula of Temple.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379948
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  • 2
    Electronic Resource
    Electronic Resource
    Orthogonalization of function spaces in the resonating group model (1985)
    Springer
    The European physical journal 321 (1985), S. 581-588 
    Details
    ISSN: 1434-601X
    Keywords: 24.10.−i ; 21.60.Gx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A coupled-channel resonating group equation for orthogonal channel spaces is derived. It follows from the common resonating group equation by a recursion relation. The recursion extracts from higher channels all overlaps with lower channels, such that the higher channels become corrections to the lower ones. A physically meaningful definition of elimination potentials becomes possible. The new coupled channel resonating group equation allows the derivation ofphysical effective potentials by eliminating small corrections, only. It also allows the derivation oftechnical potentials, i.e. potentials with an unphysical off-shell behaviour, when the dominant part of the equation is eliminated. A numerical example demonstrates that linear dependence of the test function space is not harmful to the new equation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01432433
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  • 3
    Electronic Resource
    Electronic Resource
    Off-shell behaviour of theN-N interaction in a six-quark resonating group model of the deuteron (1988)
    Springer
    Few body systems 5 (1988), S. 45-58 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional “σ”-exchange potential between neutron and proton binds the deuteron at the correct energy. Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution. Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01351268
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  • 4
    Electronic Resource
    Electronic Resource
    Formation of clusters in the nuclear surface (1988)
    Springer
    Few body systems 5 (1988), S. 107-115 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An operator formalism is constructed which allows one to calculate a movie of nuclear density plots showing the linear oscillation of two chosen fragments (clusters) in a given ground state or virtual state of a nucleus. The main ingredients of the formalism are the projection of a nuclear wave function onto a chosen antisymmetrized cluster decomposition, and the knowledge that a quantum mechanicalL=0 motion is a linear motion averaged over angles. The formalism is tested and results are discussed in the well-known cases of a shell-model description and a resonating-group-model description of8Be. It is seen that two α-clusters appear even in the surface of the compact harmonic-oscillator shell model ground-state. They are formed with higher probability in the resonating-group-model description of the more realistic8Be virtual state at 92 keV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01079582
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  • 5
    Electronic Resource
    Electronic Resource
    Numerical convergence study of the orthogonalized multi-channels approach to three-body Coulomb scattering below breakup threshold (1992)
    Springer
    Few body systems 13 (1992), S. 159-163 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The three-body Coulomb problem for nuclear clusters is solved numerically for a model below three-body breakup threshold. An orthogonalized multi-channels method is employed. The method allows to check for convergence by considering the norm square of the closed-channels part of the wave function. The numerical results show that convergence can well be achieved on present-day computers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01076397
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  • 6
    Electronic Resource
    Electronic Resource
    Orthogonalization of channel spaces in the quark resonating group model (1986)
    Springer
    Few body systems 1 (1986), S. 37-45 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A recently developed coupled-channel resonating group method with orthogonalized function spaces is tested. As test example a six-quark three-channel resonating group model is used. The channels are theNN-, ΔΔ- andCC- (“hidden colour”) channels. In earlier calculations without orthogonalization of channel spaces the relative motion function of theNN-channel had a node in theS-wave at approximately 0.5 fm. In the new treatment, in which the ΔΔ- andCC-channels are only orthogonal corrections to theNN-channel, this node is no longer present. The newNN wave function is very similar to the one of the single-channel approximation. Thus, in the one- and three-channel approximation, we consistently find that the six-quark resonating group model does not support the notion of a short-distance node in theNN wave function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01075290
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  • 7
    Electronic Resource
    Electronic Resource
    Test of effective cluster interactions by pion scattering (1986)
    Springer
    Few body systems 1 (1986), S. 203-221 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The superposition of effective interactions is studied by a cluster approach to the pion-nucleus potential with particular emphasis on the treatment of the Pauli principle between the clusters. The model is based on the formalism of Kerman, McManus, and Thaler and constructs the pion-nucleus interaction by a superposition procedure of pion-cluster interactions in the framework of the fish-bone model. The second-order contribution due to excitations of the relative motion between the clusters has been taken into account as well as true absorption. A test calculation ofΠ +_20 scattering with the cluster approach reproduces the gross structure of the differential elastic cross section and the total non-elastic cross section of conventional calculations quite well. Furthermore, it is confirmed that the three-body Pauli interaction is negligible also in the case of a realistic and rather complicated pion-nucleus interaction thus justifying the usual folding approach. The rotational bands contribute about 10% to the cross sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01076712
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  • 8
    Electronic Resource
    Electronic Resource
    A physical interpretation of the discrete ambiguities in the optical potential for composite particles (1980)
    Springer
    The European physical journal 296 (1980), S. 51-54 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the appearance of discrete ambiguities in the optical potential of composite particles is caused by the existence of partly Pauli-forbidden states. The given interpretation is tested in the case ofα-58Ni scattering atE α=50.2 MeV where seven different optical potentials give satisfactory agreement with experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415614
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  • 9
    Electronic Resource
    Electronic Resource
    A test of the fish bone optical model onα-16O scattering (1980)
    Springer
    The European physical journal 298 (1980), S. 113-119 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recently proposed fish bone optical model is tested on0α-16 O scattering. Using a microscopic interaction similar to that of resonating group calculations the characteristic rotational bands in20Ne as well as the gross structure of the elastic differential cross section are reproduced. It is shown that the fish bone optical model can be extended by inclusion of a phenomenological imaginary part. A numerical comparison with the corresponding double folding model and with the Saito model confirms the theoretical prediction that the fish bone optical model is a further step towards inclusion of the effect of the Pauli principle in the optical model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01554051
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  • 10
    Electronic Resource
    Electronic Resource
    Pauli-correct separable potentials for composite particle interactions (1981)
    Springer
    The European physical journal 299 (1981), S. 241-244 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method is presented which allows to derive separable two-cluster interaction potentials from wave functions of the fish bone optical model, or from resonating group wave functions. The two-cluster Pauli effect, as much as it is contained in the off-shell behaviour of the wave functions, is reproduced by the separable interaction. The potentials are real, symmetric and energy-independent. The α-α potential is given as an example.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01443941
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