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Nuclear Theory·nucl-th

Wednesday·February 18, 2015

7 papers—6 primary·1 cross-listed

All7Primary6Cross-lists1
  1. 01

    [Submitted on 16 Feb 2015]

    Light-Heavy Ion Collisions: A window into pre-equilibrium QCD dynamics?

    Paul Romatschke🇺🇸

    Relativistic collisions of light on heavy ions (p+Au at sqrt(s)=7.7 GeV, p+Au, d+Au,3He+Au at sqrt(s)=62.4 GeV and 200 GeV and p+Pb, 3He+Pb at sqrt(s)=5.02 TeV) are simulated using "superSONIC", a model that includes pre-equilibrium flow, viscous hydrodynamics and a hadronic cascade afterburner. Even though these systems have strong gradients and only consist of at most a few tens of charged particles per unit rapidity, one finds evidence that a hydrodynamic description applies to these systems. Based on these simulations, the presence of a triangular flow component in d+Au collisions at sqrt(s)=200 GeV is predicted to be similar in magnitude to that found in 3He+Au collisions. Furthermore, the v3(p_T) ratio of 3He+Au to d+Au is found to be sensitive to the presence of pre-equilibrium flow. This would imply an experimentally accessible window into pre-equilibrium QCD dynamics using light-heavy ion collisions.

    Comments:
    8 pages plus appendix; 9 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.04745 [pdf]
    EPJC(2015)·125 citations
  2. 02

    [Submitted on 17 Feb 2015]

    Energy-dependence of skin-mode fraction in excitations of neutron-rich nuclei

    H. Nakada · T. Inakura · H. Sawai

    We have extensively investigated characters of the low-energy strengths in nuclei, by analyzing the transition densities obtained by the HF+RPA calculations with several effective interactions. Crossover behavior has been confirmed, from the skin mode at low energy to the mode at higher energy. Decomposing the strengths into the skin-mode, -mode and interference fractions, we show that the ratio of the skin-mode strength to the full strength may be regarded as a generic function of the excitation energy, insensitive to nuclides and effective interactions, particularly beyond Ni.

    Comments:
    To appear in Proc. of CGS15
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.04790 [pdf]
    EPJ Web Conf.(2015)·0 citations
  3. 03

    [Submitted on 17 Feb 2015]

    Particle-vibration coupling effect on the -decay of magic nuclei

    Yifei Niu · Zhongming Niu · Gianluca Colo · Enrico Vigezzi

    Nuclear -decay in magic nuclei is investigated, taking into account the coupling between particle and collective vibrations,on top of self-consistent random phase approximation calculations based on Skyrme density functionals. The low-lying Gamow-Teller strength is shifted downwards and at times becomes fragmented; as a consequence, the -decay half-lives are reduced due to the increase of the phase space available for the decay. In some cases, this leads to a very good agreement between theoretical and experimental lifetimes: this happens, in particular, in the case of the Skyrme force SkM*, that can also reproduce the line shape of the high energy Gamow-Teller resonance as it was previously shown.

    Comments:
    5 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.04830 [pdf]
    PRL(2015)·92 citations
  4. 04

    [Submitted on 17 Feb 2015]

    Gamow-Teller response and its spreading mechanism in doubly magic nuclei

    Yifei Niu · Gianluca Colo · Enrico Vigezzi

    The scope of the paper is to apply a state-of-the-art beyond mean-field model to the description of the Gamow-Teller response in atomic nuclei. This topic recently attracted considerable renewed interest, due, in particular, to the possibility of performing experiments in unstable nuclei. We study the cases of Ca, Ni, Sn and Pb. Our model is based on a fully self-consistent Skyrme Hartree-Fock plus random phase approximation. The same Skyrme interaction is used to calculate the coupling between particles and vibrations, which leads to the mixing of the Gamow-Teller resonance with a set of doorway states and to its fragmentation. We compare our results with available experimental data. The microscopic coupling mechanism is also discussed in some detail.

    Comments:
    27 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.04836 [pdf]
    PRC(2014)·56 citations
  5. 05

    [Submitted on 17 Feb 2015]

    Core excitation in three-body nuclear reactions: Improved nucleon-core potential

    A. Deltuva

    Three-body nuclear reactions in two-nucleon plus core systems are described in the framework of exact scattering equations including the core excitation. A nucleon-core optical potential is constructed that can be easily adjusted to the reference potential and thereby to the experimental two-body data, if available. This constitutes an important improvement over the simple deformation of the potential used previously that violated the original fit to the data. Predictions for elastic, inelastic, and transfer reactions involving and nuclear cores are obtained. The new optical potential leads to a moderate increase of cross sections.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.04913 [pdf]
    PRC(2015)·16 citations
  6. 06

    [Submitted on 17 Feb 2015]

    Effect of the symmetry energy and hyperon interaction on neutron stars

    Daniel Bizarro🇵🇹 · Aziz Rabhi🇵🇹 · Constança Providência🇵🇹

    The joint effect of the density dependence of the symmetry energy and strangeness content on the structure of cold neutron stars is studied within the framework of a relativistic mean field theory. It is shown that 2 are obtained for repulsive interaction and preferably for a small or a large slope . An attractive potential in nuclear matter will favor the appearance of strangeness in stars with a mass as small as , if, however it is repulsive only stars with a mass will contain strangeness. The joint effect of reducing the symmetry energy slope and including hyperons is to farther reduce the radius. Neutron star maximum mass evolve non-monotonically with the symmetry energy slope, and the smallest masses are obtained for values MeV. Other neutron star variables evolve nonlinearly with the slope of the symmetry energy and depend on the hyperon-nucleon and hyperon-hyperon couplings. The radius of a neutron star is linearly correlated with the neutron star total strangeness fraction and the slope is independent of the slope of the symmetry energy and the mass of the star.

    Comments:
    16 pages, 13 figures, 9 tables, submitted to Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.04952 [pdf]
    8 citations

Affiliations

first authorsco-authorsvia INSPIRE