Features of exceptional points and the continuum spectroscopy

We discuss observable features of exceptional points and the resonance spectroscopy of $^{16}$Ne using the Shell Model Embedded in the Continuum.Comment: 10 pages, 4 figures Zakopane Conference on Nuclear Physics, September 1-7, 2008, Zakopane, Polan

Structure of many-body continuum states in the proximity of exceptional points

We demonstrate existence of exceptional points in many-body scattering continuum of atomic nucleus and discuss their salient effects on the example of one-nucleon spectroscopic factors.Comment: 5 pages, 4 figure

Hard Photons Beyond Proton-Neutron Bremsstrahlung in Heavy-Ion Collisions

We report on the study of extremely high energy photons, pions and etas, produced in intermediate energy heavy-ion collisions. Possibility of imaging the final-state phase space in these collisions by the Bose-Einstein correlations for photons is critically examined.Comment: 11 pages, 4 figures, Invited talk at the NATO Advanced Research Workshop on the Structure of Mesons, Baryons and Nuclei, Krakow (Poland), May 26 - 30, 199

On the origin of nuclear clustering

Clustering is one of the most complex phenomena known to the structure of atomic nuclei. A comprehensive description of this ubiquitous phenomenon goes beyond standard shell model and cluster model frameworks. We argue that clustering is a consequence of an openness of the nuclear many-body system. To illustrate this point, we study the near-threshold behavior of exceptional points in ^16 Ne and ^24 S.Comment: Proceedings "Frontier Issues in Physics of Exotic Nuclei" (YKIS2011/DCEN2011), 14 pages, 9 figure

Unexpected features of quantum degeneracies in a pairing model with two integrable limits

The evolution pattern of level crossings and exceptional points is studied in a non-integrable pairing model with two different integrable limits. One of the integrable limits has two independent parameter-dependent integrals of motion. We demonstrate, and illustrate in our model, that quantum integrability of a system with more than one parameter-dependent integral of motion is always signaled by level crossings of a complex-extended Hamiltonian. We also find that integrability implies a reduced number of exceptional points. Both properties could uniquely characterize quantum integrability in small Hilbert spaces.Comment: 4 pages, 2 figure

Approximate solution of the pairing Hamiltonian in the Berggren basis

We derive the approximate solution for the pairing Hamiltonian in the Berggren ensemble of single particle states including bound, resonance and non-resonant scattering states. We show that this solution is reliable in the limit of a weak pairing interaction

Weakly bound systems, continuum effects, and reactions

Structure of weakly bound/unbound nuclei close to particle drip lines is different from that around the valley of beta stability. A comprehensive description of these systems goes beyond standard Shell Model and demands an open quantum system description of the nuclear many-body system. We approach this problem using the Gamow Shell Model which provides a fully microscopic description of bound and unbound nuclear states, nuclear decays, and reactions. We present in this paper the first application of the GSM for a description of the elastic and inelastic scattering of protons on 6He.Comment: Proc. Int. Conf. "Horizons of Innovative Theories, Experiments and Supercomputing in Nuclear Physics", June 4-7, 2012, New Orleans, Luisiana, USA; 10 pages, 4 figure

Isospin mixing and the continuum coupling in weakly bound nuclei

The isospin breaking effects due to the Coulomb interaction in weakly-bound nuclei are studied using the Gamow Shell Model, a complex-energy configuration interaction approach which simultaneously takes into account many-body correlations between valence nucleons and continuum effects. We investigate the near-threshold behavior of one-nucleon spectroscopic factors and the structure of wave functions along an isomultiplet. Illustrative calculations are carried out for the T=1 isobaric triplet. By using a shell-model Hamiltonian consisting of an isoscalar nuclear interaction and the Coulomb term, we demonstrate that for weakly bound or unbound systems the structure of isobaric analog states varies within the isotriplet and impacts the energy dependence of spectroscopic factors. We discuss the partial dynamical isospin symmetry present in isospin-stretched systems, in spite of the Coulomb interaction that gives rise to large mirror symmetry breaking effects.Comment: 10 pages, 5 figures ; published versio