PaperPanorama
FAQ

Nuclear Theory·nucl-th

Thursday·June 18, 2020

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 01

    [Submitted on 16 Jun 2020]

    Is perturbative study of ground-state correlations valid?

    Mitsuru Tohyama

    Perturbative approaches have often been used to include the effects of ground-state correlations in extended theories of the random-phase approximation. Validity of such approaches is investigated for a solvable model where comparison with exact solutions can be made. It is pointed out that there is a case where perturbative approaches give good results in spite of the fact that interaction strength is far beyond a perturbative region.

    Comments:
    6 pages,11 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2006.09561 [pdf]
    0 citations
  2. 02

    [Submitted on 17 Jun 2020]

    Study of Charge Radii with Neural Networks

    Di Wu🇨🇳 · C.L. Bai🇨🇳 · H. Sagawa🇯🇵 · H.Q. Zhang🇨🇳

    A feed-forward neural network model is trained to calculate the nuclear charge radii. The model trained with input data set of proton and neutron number , the electric quadrupole transition strength from the first excited 2 state to the ground state, together with the symmetry energy. The model reproduces well not only the isotope dependence of charge radii, but also the kinks of charge radii at the neutron magic numbers for Sn and Sm isotopes, and also for Pb isotopes. The important role of value is pointed out to reproduce the kink of the isotope dependence of charge radii in these nuclei. Moreover, with the inclusion of the symmetry energy term in the inputs, the charge radii of Ca isotopes are well reproduced. This result suggests a new correlation between the symmetry energy and charge radii of Ca isotopes. The Skyrme HFB calculation is performed to confirm the existence of this correlation in a microscopic model.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2006.09677 [pdf]
    PRC(2020)·84 citations
  3. 03

    [Submitted on 17 Jun 2020]

    On a quasi-bound state in the system caused by strong interactions

    N.V. Shevchenko🇨🇿

    It was found that potential could influence the results of the quasi-bound state search in the system, where the corresponding pole is situated close to the threshold. Three-body Faddeev-type calculations of the system performed with a new model of nucleon-nucleon interaction predict the existence of the quasi-bound state caused by strong interactions. Its binding energy is small ( MeV), while the width is comparable with the width of the quasi-bound state ( MeV).

    Comments:
    8 pages, 2 figures, 4 tables; v2: minor changes in Section 2, additional information about the NN potential in Section 3; accepted to the special issue of Few-Body Systems journal "New Trends in Hadron Physics: a Few-Body Perspective"
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2006.09800 [pdf]
    Few Body Syst.(2020)·8 citations
  4. 04

    [Submitted on 17 Jun 2020]

    Properties of a separable representation of optical potentials

    Michael Quinonez · Linda Hlophe · Filomena Nunes

    Background: Separable interactions have a long history in nuclear physics. In the last few years, separable expansions have been used to represent the optical potential between a nucleon (proton or neutron) and a target. Purpose: We explore the non-local properties of these separable optical potentials as well as their convergence behavior. Method: For a couple of cases, we use the generalized Ersnt-Shakin-Thaler scheme to generate separable interactions starting from local optical potentials. We study the variation of the interaction with energy range and rank. Results: We find that, overall the off-diagonal behavior of the converged separable interaction deviates from the Gaussian form assumed by Perey and Buck. However, in the region surrounding the maximum depth the Gaussian form works quite well. Focusing on this region, we study potentials describing neutron elastic scattering on O and Ca for beam energies in the range of 10-50 MeV and explore several measures of non-locality of the separable interactions. Conclusions: When the energy range considered for generating the separable interaction is MeV, the resulting non-locality is large and target dependent. Contrarily, the nonlocality obtained including larger energy ranges in the separable procedure is independent of the target and other details of the original local potential. We find that, even when including in the expansion many support points with energy ranges MeV, the resulting potential retains non-local behavior. Connections with microscopic optical potentials as well as other transformations used in the nucleon-nucleon domain are made.

    Comments:
    9 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2006.09926 [pdf]
    PRC(2020)·2 citations
  5. 05

    [Submitted on 17 Jun 2020]

    X(3872) Transport in Heavy-Ion Collisions

    Biaogang Wu🇺🇸 · Xiaojian Du🇩🇪 · Matthew Sibila🇺🇸 · Ralf Rapp🇺🇸

    The production of the particle in heavy-ion collisions has been contemplated as an alternative probe of its internal structure. To investigate this conjecture, we perform transport calculations of the through the fireball formed in nuclear collisions at the LHC. Within a kinetic-rate equation approach as previously used for charmonia, the formation and dissociation of the is controlled by two transport parameters, i.e., its inelastic reaction rate and thermal-equilibrium limit in the evolving hot QCD medium. While the equilibrium limit is controlled by the charm production cross section in primordial nucleon-nucleon collisions (together with the spectra of charm states in the medium), the structure information is encoded in the reaction rate. We study how different scenarios for the rate affect the centrality dependence and transverse-momentum () spectra of the . Larger reaction rates associated with the loosely bound molecule structure imply that it is formed later in the fireball evolution than the tetraquark and thus its final yields are generally smaller by around a factor of two, which is qualitatively different from most coalescence model calculations to date. The spectra provide further information as the later decoupling time within the molecular scenario leads to harder spectra caused by the blue-shift from the expanding fireball.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    2006.09945 [pdf]
    EPJA(2021)·75 citations

Affiliations

first authorsco-authorsvia INSPIRE