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Milano, Italy

We perform calculations for the binding energies and low-lying levels of 10,11,12,13,14,15,16,17,18,19,20,21,22C nuclei starting from the chiral N3LO nucleon-nucleon potential within the framework of the Hybrid Multideterminant scheme. The effective interaction is obtained using the Lee-Suzuki renormalization scheme applied to 4 and in some cases to 5, major harmonic oscillator shells. The results are compared with the experimental data. Source


Paavola J.,University of Turku | Hall M.J.W.,Australian National University | Paris M.G.A.,DellUniversity Milan | Maniscalco S.,University of Turku | Maniscalco S.,Heriot - Watt University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The transition from quantum to classical, in the case of a quantum harmonic oscillator, is typically identified with the transition from a quantum superposition of macroscopically distinguishable states, such as the Schrödinger-cat state, into the corresponding statistical mixture. This transition is commonly characterized by the asymptotic loss of the interference term in the Wigner representation of the cat state. In this paper we show that the quantum-to-classical transition has different dynamical features depending on the measure for nonclassicality used. Measures based on an operatorial definition have well-defined physical meaning and allow a deeper understanding of the quantum-to-classical transition. Our analysis shows that, for most nonclassicality measures, the Schrödinger-cat state becomes classical after a finite time. Moreover, our results challenge the prevailing idea that more macroscopic states are more susceptible to decoherence in the sense that the transition from quantum to classical occurs faster. Since nonclassicality is a prerequisite for entanglement generation our results also bridge the gap between decoherence, which is lost only asymptotically, and entanglement, which may show a "sudden death." In fact, whereas the loss of coherences still remains asymptotic, we emphasize that the transition from quantum to classical can indeed occur at a finite time. © 2011 American Physical Society. Source


A simple and general prescription for evaluating unambiguously the sign of the grand canonical trace of quasi-particle statistical density operators (the so-called sign ambiguity in taking the square root of determinants) is given. Sign ambiguities of this kind appear in the evaluation of the grand canonical partition function projected to good quantum numbers (angular momentum, parity and particle number) in the Hartree-Fock-Bogoliubov approximation at finite temperature, since traces are usually expressed as the square root of determinants. A comparison is made with the numerical continuity method. Source


Dibitetto G.,University of Groningen | Klemm D.,DellUniversity Milan | Klemm D.,National Institute of Nuclear Physics, Italy
Journal of High Energy Physics | Year: 2010

We discuss the issue of how to include magnetic charges in the AdS 4 superalgebra osp(4|2). It is shown that the usual way of introducing a pseudoscalar central charge on the right hand side of the basic anticommutator does not work, because this breaks SO(2, 3) covariance. We propose a way out by promoting the magnetic charge to a vector charge, which amounts to enlarge osp(4|2) to the superconformal algebra su(2, 2|1). The conditions for 1/4, 1/2 and 3/4 BPS states are then analyzed. These states form the boundary of the convex cone associated with the Jordan algebra of 4×4 complex hermitian matrices. An Inönü-Wigner contraction of the constructed superalgebra yields a known extension of the Poincaré superalgebra containing electric and magnetic 0-brane charges as well as string- and space-filling 3-brane charges. As an example, we show how some supersymmetric AdS4 black holes fit into the classification scheme of BPS states. Source


Puddu G.,DellUniversity Milan
European Physical Journal A | Year: 2015

Using the Argonne V18 interaction, renormalized with the Lee-Suzuki method, we study nuclei around the N = 20 island of inversion. We include 5 major oscillator shells, in a no-core approach, using the hybrid multi-determinant method reaching up to few hundreds Slater determinants. Although qualitatively in agreement with the experimental levels, the calculated BE2 do not show the same amount of collectivity seen experimentally. © 2015, SIF, Springer-Verlag Berlin Heidelberg. Source

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