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Nuclear Theory·nucl-th

Wednesday·November 18, 2020

10 papers—3 primary·7 cross-listed

All10Primary3Cross-lists7
  1. 01

    [Submitted on 16 Nov 2020]

    Rotational bands beyond the Elliott model

    Ryan Zbikowski · Calvin W. Johnson · Anna E. McCoy · Mark A. Caprio · Patrick J. Fasano

    Rotational bands are commonplace in the spectra of atomic nuclei. Inspired by early descriptions of these bands by quadrupole deformations of a liquid drop, Elliott constructed a discrete nucleon representations of from fermionic creation and annihilation operators. Ever since, Elliott's model has been foundational to descriptions of rotation in nuclei. Later work, however, suggested the symplectic extension provides a more unified picture. We decompose no-core shell-model nuclear wave functions into symmetry-defined subspaces for several beryllium isotopes, as well as Ne, using the quadratic Casimirs of both Elliott's and . The band structure, delineated by strong values, has a more consistent description in rather than . {In particular, we confirm previous work finding in some nuclides strongly connected upper and lower bands with the same underlying symplectic structure.

    Comments:
    30 pages, 15 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2011.08307 [pdf]
    J.Phys.G(2021)·7 citations
  2. 02

    [Submitted on 17 Nov 2020]

    Plasma shielding effects on nuclear spectra: Ne application

    Serkan Akkoyun · M. Kemal Bahar

    In this study, for the first time, in particular to astrophysics and fusion studies, how atomic nuclei embedded in the plasma environment are affected by plasma are systematically analysed. The related interactions in plasma environments considered as Debye and quantum plasma are depicted by more general exponential cosine screened Coulomb (MGECSC) potential. The plasma effects on the change of nuclear energy levels are probed through computations performed within the nuclear shell-model framework. For this purpose, the single-particle energy (spe) values to be used in the calculations are obtained by considering the modified Woods-Saxon (WS) potential due to shielding effect of plasma environment. As the modification in question is executed on Coulomb interaction term in WS potential, the computations are carried out for Ne nucleus which has two valence protons. Under the influence of the plasma, it is confirmed that the spe's change within certain limit value ranges. When considering the nuclear shell-model for the related computing, it is clear that this change leads to an obvious shifting in the energies of the nuclear states. It is observed that proton spe values are sensitive to plasma shielding effect, and shielding effect has a significant potent on the ground-state and excited energy states of the nucleus. In particular, the ground-state binding energies are determined to be extremely sensitive to the plasma shielding parameters. Plasma environments affect the proton spe and ground state energy (gse) in the same way. The alternative to each other of plasma shielding parameters on the spe, gse and excited energy levels is also analysed.

    Comments:
    Major revision is needed
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.08452 [pdf]
    Bull.Russ.Acad.Sci.Phys.(2022)·0 citations
  3. 03

    [Submitted on 17 Nov 2020]

    Linear Response Theory with finite-range interactions

    Dany Davesne🇫🇷 · Alessandro Pastore🇬🇧 · Jesus Navarro🇪🇸

    This review focuses on the calculation of infinite nuclear matter response functions using phenomenological finite-range interactions, equipped or not with tensor terms. These include Gogny and Nakada families, which are commonly used in the literature. Because of the finite-range, the main technical difficulty stems from the exchange terms of the particle-hole interaction. We first present results based on the so-called Landau and Landau-like approximations of the particle-hole interaction. Then, we review two methods which in principle provide numerically exact response functions. The first one is based on a multipolar expansion of both the particle-hole interaction and the particle-hole propagator and the second one consists in a continued fraction expansion of the response function. The numerical precision can be pushed to any degree of accuracy, but it is actually shown that two or three terms suffice to get converged results. Finally, we apply the formalism to the determination of possible finite-size instabilities induced by a finite-range interaction.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2011.08817 [pdf]
    PPNP(2021)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE