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Nuclear Theory·nucl-th

Wednesday·September 14, 2016

13 papers—5 primary·8 cross-listed

All13Primary5Cross-lists8
  1. 01

    [Submitted on 13 Sept 2016]

    Collisions of Small Nuclei in the Thermal Model

    J. Cleymans🇿🇦 · B. Hippolyte🇫🇷 · H. Oeschler🇩🇪 · K. Redlich🇩🇪 · N. Sharma🇮🇳

    An analysis is presented of the expectations of the thermal model for particle production in collisions of small nuclei. The maxima observed in particle ratios of strange particles to pions as a function of beam energy in heavy ion collisions, are reduced when considering smaller nuclei. Of particular interest is the ratio shows the strongest maximum which survives even in collisions of small nuclei.

    Comments:
    7 pages, 4 figures, conference Critical Point and Onset of Deconfinement CPOD2016, University of Wroclaw, Poland
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1609.03700 [pdf]
    Acta Phys.Polon.Supp.(2017)·0 citations
  2. 02

    [Submitted on 13 Sept 2016]

    Phonon-particle coupling effects in single-particle energies of semi-magic nuclei

    E.E. Saperstein · M. Baldo · S.S. Pankratov · S.V. Tolokonnikov

    A method is presented to evaluate the particle-phonon coupling (PC) corrections to the single-particle energies (SPEs) in semi-magic nuclei. In such nuclei always there is a collective low-lying phonon, and a strong mixture of single-particle and particle-phonon states often occurs. As in magic nuclei, the so-called approximation, where is the vertex of the -phonon creation, can be used for finding the PC correction to the initial mass operator . In addition to the usual pole diagram, the phonon "tadpole" diagram is also taken into account. In semi-magic nuclei, the perturbation theory in with respect to is often invalid for finding the PC corrected SPEs. Instead, the Dyson equation with the mass operator is solved directly, without any use of the perturbation theory. Results for a chain of semi-magic Pb isotopes are presented.

    Comments:
    6 pages, 4 figures, 3 tables; v2 -- small corrections in the text; to be published in JETP Letters
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1609.03761 [pdf]
    JETP Lett.(2016)·8 citations
  3. 03

    [Submitted on 13 Sept 2016]

    Light-Front spin-dependent Spectral Function and Nucleon Momentum Distributions for a Three-Body System

    Alessio Del Dotto🇮🇹 · Emanuele Pace🇮🇹 · Giovanni Salmè🇮🇹 · Sergio Scopetta🇮🇹

    Poincare' covariant definitions for the spin-dependent spectral function and for the momentum distributions within the light-front Hamiltonian dynamics are proposed for a three-fermion bound system, starting from the light-front wave function of the system. The adopted approach is based on the Bakamjian-Thomas construction of the Poincare' generators, that allows one to easily import the familiar and wide knowledge on the nuclear interaction into a light-front framework. The proposed formalism can find useful applications in refined nuclear calculations, like the ones needed for evaluating the EMC effect or the semi-inclusive deep inelastic cross sections with polarized nuclear targets, since remarkably the light-front unpolarized momentum distribution by definition fulfills both normalization and momentum sum rules. It is also shown a straightforward generalization of the definition of the light-front spectral function to an A-nucleon system.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1609.03804 [pdf]
    PRC(2017)·23 citations
  4. 04

    [Submitted on 11 Sept 2016]

    Microscopic Calculations of Vortex-Nucleus Interaction in the Neutron Star Crust

    Kazuyuki Sekizawa · Gabriel Wlazłowski · Piotr Magierski · Aurel Bulgac · Michael McNeil Forbes

    We investigate the dynamics of a quantized vortex and a nuclear impurity immersed in a neutron superfluid within a fully microscopic time-dependent three-dimensional approach. The magnitude and even the sign of the force between the quantized vortex and the nuclear impurity have been a matter of debate for over four decades. We determine that the vortex and the impurity repel at neutron densities, 0.014 fm and 0.031 fm, which are relevant to the neutron star crust and the origin of glitches, while previous calculations have concluded that the force changes its sign between these two densities and predicted contradictory signs. The magnitude of the force increases with the density of neutron superfluid, while the magnitude of the pairing gap decreases in this density range.

    Comments:
    4 pages, 2 figures, Talk given at the 14th International Symposium on "Nuclei in the Cosmos" (NIC-XIV), June 19-24, 2016, Toki Messe, Niigata, Japan
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); Superconductivity (cond-mat.supr-con)
    arXiv:
    1609.03865 [pdf]
    JPS Conf.Proc.(2017)·1 citation
  5. 05

    [Submitted on 13 Sept 2016]

    meson self-energy in nuclear matter from resonant interactions

    D. Cabrera🇪🇸 · A. N. Hiller Blin🇪🇸 · M. J. Vicente Vacas🇪🇸

    The -meson properties in cold nuclear matter are investigated by implementing resonant interactions as described in effective approaches including the unitarization of scattering amplitudes. Several -like states are dynamically generated in these models around GeV, in the vicinity of the threshold. We find that both these states and the non-resonant part of the amplitude contribute sizably to the collisional self-energy at finite nuclear density. These contributions are of a similar strength as the widely studied medium effects from the cloud. Depending on model details (position of the resonances and strength of the coupling to ) we report a broadening up to about - MeV, to be added to the in-medium decay width, and an attractive optical potential at threshold up to about MeV at normal matter density. The spectral function develops a double peak structure as a consequence of the mixing of resonance-hole modes with the quasi-particle peak. The former results point in the direction of making up for missing absorption as reported in nuclear production experiments.

    Comments:
    17 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1609.03880 [pdf]
    PRC(2017)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE