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Nuclear Theory·nucl-th

Monday·October 31, 2022

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 28 Oct 2022]

    The lowest excited states of 14C and 14O nuclei within a five-cluster model

    B. E. Grinyuk · D. V. Piatnytskyi · V.S. Vasilevsky

    We study the ground and the first excited states of two mirror nuclei C and O within a five-cluster model (three alpha-particles and two extra nucleons) with the use of high accuracy variational approach with Gaussian bases. The first excited state of these nuclei is shown to be connected with a change of the structure of the two-nucleon subsystem moving in the field of the C cluster. The density distributions, electric form factors (both the elastic and transition ones), pair correlation functions, and the momentum distributions of the constituent particles are found. The most probable shapes of five-cluster systems are revealed.

    Comments:
    25 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2210.15891 [pdf]
    NPA(2023)·2 citations
  2. 02

    [Submitted on 28 Oct 2022]

    Islands of shape coexistence from single-particle spectra in covariant density functional theory

    Dennis Bonatsos · K.E. Karakatsanis · Andriana Martinou · T.J. Mertzimekis · N. Minkov

    Using covariant density functional theory with the DDME2 functional and labeling single-particle energy orbitals by Nilsson quantum numbers, a search for particle-hole (p-h) excitations connected to the appearance of shape coexistence is performed for Z=38 to 84. Islands of shape coexistence are found near the magic numbers Z=82 and Z=50, restricted in regions around the relevant neutron midshells N=104 and N=66 respectively, in accordance to the well accepted p-h interpretation of shape coexistence in these regions, which we call neutron-induced shape coexistence, since the neutrons act as elevators creating holes in the proton orbitals. Similar but smaller islands of shape coexistence are found near N=90 and N=60, restricted in regions around the relevant proton midshells Z=66 and Z=39 respectively, related to p-h excitations across the 3-dimensional isotropic harmonic oscillator (3D-HO) magic numbers N=112 and N=70, which correspond to the beginning of the participation of the opposite parity orbitals 1i13/2 and 1h11/2 respectively to the onset of deformation. We call this case proton-induced shape coexistence, since the protons act as elevators creating holes in the neutron orbitals, thus offering a possible microscopic mechanism for the appearance of shape coexistence in these regions. In the region around N=40, Z=40, an island is located on which both neutron p-h excitations and proton p-h excitations are present.

    Comments:
    21 pages, 17 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2210.16067 [pdf]
    PRC(2022)·29 citations
  3. 03

    [Submitted on 28 Oct 2022]

    Bremsstrahlung as a probe of baryon stopping in heavy-ion collisions

    Sigurd Nese🇳🇴 · Joakim Nystrand🇳🇴

    In collisions between heavy ions at ultra-relativistic energies the participating protons lose energy, which is converted into new particles. As the protons slow down, they emit bremsstrahlung radiation. The yield and angular distribution of the emitted radiation are sensitive probes of how much energy the incoming protons have lost. In this paper, the spectrum of bremsstrahlung radiation is calculated for different stopping scenarios, and the results are compared with the expected yield of photons from hadronic interactions.

    Comments:
    15 pages, 5 figures. Added one reference and one figure. Corrected a few typos
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2210.16200 [pdf]
    EPJC(2023)·2 citations
  4. 04

    [Submitted on 28 Oct 2022]

    Is the "RG-invariant EFT'' for few-nucleon systems cutoff independent?

    A. M. Gasparyan🇩🇪 · E. Epelbaum🇩🇪

    We consider nucleon-nucleon scattering using the formulation of chiral effective field theory which is claimed to be renormalization group invariant. The cornerstone of this framework is the existence of a well-defined infinite-cutoff limit for the scattering amplitude at each order of the expansion, which should not depend on a particular regulator form. Focusing on the partial wave as a representative example, we show that this requirement can in general not be fulfilled beyond the leading order, in spite of the perturbative treatment of subleading contributions to the amplitude. Several previous studies along these lines, including the next-to-leading order calculation by Long and Yang [Phys. Rev. C84, 057001 (2011)] and a toy model example with singular long-range potentials by Long and van Kolck [Annals Phys. 323, 1304-1323 (2008)], are critically reviewed and scrutinized in detail.

    Comments:
    28 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2210.16225 [pdf]
    PRC(2023)·30 citations

Affiliations

first authorsco-authorsvia INSPIRE