arXiv subjects

Gianluca Colò

Publications and source records attributed to Gianluca Colò.

39 records · Page 3Linked to original sources

arXiv2012

Continuum particle-vibration coupling method in coordinate-space representation for finite nuclei

In this paper we present a new formalism to implement the nuclear particle-vibration coupling (PVC) model. The key issue is the proper treatment of the continuum, that is allowed by the coordinate space representation. Our formalism, based on the use of zero-range interactions like the Skyrme forces, is microscopic and fully self-consistent. We apply it to the case of neutron single-particle states in $^{40}$Ca, $^{208}$Pb and $^{24}$O. The first two cases are meant to illustrate the comparison with the usual (i.e., discrete) PVC model. However, we stress that the present approach allows to calculate properly the effect of PVC on resonant states. We compare our results with those from experiments in which the particle transfer in the continuum region has been attempted. The latter case, namely $^{24}$O, is chosen as an example of a weakly-bound system. Such a nucleus, being double-magic and not displaying collective low-lying vibrational excitations, is characterized by quite pure neutron single-particle states around the Fermi surface.

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arXiv2011

Microscopic theory of the γ-decay of nuclear giant resonances

In the past decades, the γ-decay of giant resonances has been studied using phenomenological models. In keeping with possible future studies performed with exotic beams, microscopically-based frameworks should be envisaged. In the present paper, we introduce a model which is entirely based on Skyrme effective interactions, and treats the ground-state decay within the fully self-consistent Random Phase Approximation (RPA) and the decay to low-lying states at the lowest order beyond RPA. The model is applied to 208Pb and 90Zr, and the results are compared with experimental data.

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arXiv2011

Subtraction of the spurious translational mode from the RPA response function

It is well known that within self-consistent Random Phase Approximation (RPA) on top of Hartree-Fock (HF), the translational symmetry should be restored. Due to approximations at the level of the practical implementation, this restoration may be only partial. As a result, one has spurious contributions in the physical quantities that are extracted from RPA. While there are several recipes in the literature to overcome this drawback in order to produce transition densites or strength functions that are free from spurious contamination, there is no formalism associated with the full RPA response function. We present such formalism in this paper. Our goal is to avoid spurious contamination when the response function is used in many-body frameworks like the particle-vibration coupling theory.

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