L. Van Daele

Nuclear overlap functions determined by the asymptotic behavior of the one-body density matrix

D. Van Neck, L. Van Daele, Y. Dewulf, M. Waroquier

Physical Review C

56 (3), 1398-1409

1997

A1

Published while none of the authors were employed at the CMM

Abstract

Single-particle overlap functions and spectroscopic factors are calculated using the asymptotic behavior in coordinate space of the one-body density matrix corresponding to a many-body wave function in correlated basis function theory. We include state-dependent correlation functions and discriminate between the effects of central, spin-spin, and tensor correlations. The method is applied to ¹⁶O. We also discuss the effect of center-of-mass motion on the calculated spectroscopic factors.

DOI

http://dx.doi.org/10.1103/PhysRevC.56.1398

Long-range correlations in finite nuclei: comparison of two self-consistent treatments

Y. Dewulf, D. Van Neck, L. Van Daele, M. Waroquier

Physics Letters B

396, 7-14

1997

A1

Published while none of the authors were employed at the CMM

Abstract

Long-range correlations, which are partially responsible for the observed fragmentation and depletion of low-lying single-particle strength, are studied in the Green's function formalism. The self-energy is expanded up to second order in the residual interaction. We compare two methods of implementing self-consistency in the solution of the Dyson equation beyond Hartree-Fock, for the case of the 16O nucleus. It is found that the energy-bin method and the BAGEL method lead to globally equivalent results. In both methods the final single-particle strength functions are characterized by exponential tails at energies far from the Fermi level.

DOI

http://dx.doi.org/10.1016/S0370-2693(97)00135-4

Compton Scattering on the Proton and Light Nuclei in the \Delta-Resonance Region

L. Van Daele, D. Van Neck, M. Waroquier, A.Y. Korchin

Acta Physica Polonica B

33(3), 847-871

2002

A1

Abstract

Microscopic calculations of Compton scattering on the free proton and light nuclei are presented. For the description of Compton scattering on the proton the conventional K-matrix approach and the ``Dressed K-Matrix'' model are introduced. The latter approach can be used to calculate polarizabilities as well as Compton scattering for photon energies upto 1 GeV since it obeys the symmetry properties which are appropriate in the different energy regions. In particular, crossing symmetry, gauge invariance and unitarity are satisfied. The extent of violation of analyticity (causality) is used as an expansion parameter. Coherent Compton scattering on light nuclei at 200--300 MeV is studied in the impulse approximation and is shown to be a sensitive probe of the in-medium properties of the \Delta -resonance. Modifications of the properties of the \Delta-resonance due to the nuclear medium are accounted for through the self-energy operator of the \Delta. The dominant medium effects such as the Pauli blocking effects in the decay width, effective nucleon mass and particle--hole excitations in the pion propagator are consistently included in nuclear matter.

DOI

http://dx.doi.org/

Coherent Compton scattering on light nuclei in the Δ-resonance region

L. Van Daele, A.Y. Korchin, D. Van Neck, O. Scholten, M. Waroquier

Physical Review C

65 (1), 014613

2001

A1

Abstract

Coherent Compton scattering on light nuclei in the Δ-resonance region is studied in the impulse approximation and is shown to be a sensitive probe of the in-medium properties of the Δ resonance. The elementary amplitude on a single nucleon is calculated from the unitary K-matrix approach developed previously. Modifications of the properties of the Δ resonance due to the nuclear medium are accounted for through the self-energy operator of the Δ, calculated from the one-pion loop. The dominant medium effects such as the Pauli blocking, mean-field modification of the nucleon and Δ masses, and particle-hole excitations in the pion propagator are consistently included in nuclear matter.