Eur. Phys. J. A 10, 157-169
Non-local potentials and rotational bands of resonances in ion collisions
E. De Micheli1 and G.A. Viano21 Istituto di Cibernetica e Biofisica, Consiglio Nazionale delle Ricerche, Via De Marini 6, 16149 Genova, Italy
2 Dipartimento di Fisica, Università di Genova, Istituto Nazionale di Fisica Nucleare - Sez. di Genova, Via Dodecaneso 33, 16146 Genova, Italy
demic@icb.ge.cnr.it
viano@ge.infn.it
(Received: 29 June 2000 / Revised version: 14 December 2000 Communicated by A. Molinari)
Abstract
Sequences of rotational resonances (rotational bands)
and corresponding antiresonances are observed in ion collisions.
In this paper we propose a description which
combines collective and single-particle features of
cluster collisions. It is shown how rotational bands emerge in many-body dynamics, when the
degeneracies proper of the harmonic oscillator spectra are removed by adding interactions depending on
the angular momentum.
These interactions can be properly introduced in connection with the exchange forces and the antisymmetrization,
and give rise to a class of non-local potentials whose spectral properties are analyzed in detail.
In particular, we give a classification of the singularities of the resolvent, which are associated
with bound states and resonances. The latter are then studied using an appropriate type of
collective coordinates, and a hydrodynamical model of the trapping, responsible for the resonances,
is then proposed. Accordingly, we derive, from the uncertainty principle, a spin-width of the
unstable states which can be related to their angular lifetime.
25.70.-z - Low and intermediate energy heavy-ion reactions.
25.70.Ef - Resonances.
25.70.Bc - Elastic and quasielastic scattering.
© Società Italiana di Fisica, Springer-Verlag 2001
