Particle-unstable light nuclei with a Sturmian approach that preserves the Pauli principle.pdf

a r X i v : n u c l - t h / 0 7 0 1 0 1 4 v 1 5 J a n 2 0 0 7 1 Particle-unstable light nuclei with a Sturmian approach that preserves the Pauli principle. L. Cantona, K. Amosb, S. Karataglidisc, G. Pisenta, J. P. Svenned, D. van der Knijffe a Istituto Nazionale di Fisica Nucleare, e Dipartimento di Fisica dell’Universita?, via Marzolo 8, Padova I-35131, Italia, b School of Physics, The University of Melbourne, Victoria 3010, Australia c Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa d Department of Physics and Astronomy, University of Manitoba, and WITP, Winnipeg, MB, Canada R3T 2N2 e Advanced Research Computing, Information Div., The University of Melbourne, Australia Sturmian theory for nucleon-nucleus scattering is discussed in the presence of all the phenomenological ingredients necessary for the description of weakly-bound (or particle- unstable) light nuclear systems. Currently, we use a macroscopic potential model of collective nature. The analysis shows that the couplings to low-energy collective-core excitations are fundamental but they are physically meaningful only if the constraints introduced by the Pauli principle are taken into account. The formalism leads one to discuss a new concept, Pauli hindrance, which appears to be important to understand the structure of weakly-bound and unbound systems. 1. Sturmians Sturmians provide the solution of the scattering problems by matrix manipulation and represent an efficient formalism for determination of S-matrix, and scattering wave func- tions, bound states and resonances [ 1]. They work well with non-local interactions (such as those non localities arising from the effects due to Pauli exchanges). They allow a consistent treatment of Coulomb plus nuclear interactions, as well as the inclusion in the scattering process of coupled-channel (CC) dynamics. This occurs, for instance, when strong coupling to low-lying excitations of the target nucleus have to be taken