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Nuclear Theory·nucl-th

Tuesday·December 20, 2022

16 papers—6 primary·10 cross-listed

All16Primary6Cross-lists10
  1. 01

    [Submitted on 17 Dec 2022]

    Quantum computing of the pairing Hamiltonian at finite temperatures

    Chongji Jiang🇨🇳 · Junchen Pei🇨🇳

    In this work, we study the pairing Hamiltonian with four particles at finite temperatures on a quantum simulator and a superconducting quantum computer. The excited states are obtained by the variational quantum deflation (VQD). The error-mitigation methods are applied to improve the noisy results. The simulation of thermal excitation states is performed using the same variational circuit as at zero temperature. The results from quantum computing become close to exact solutions at high temperatures, and demonstrate a smooth superfluid-normal phase transition as a function of temperatures as expected in finite systems.

    Comments:
    10 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2212.08862 [pdf]
    PRC(2023)·5 citations
  2. 02

    [Submitted on 17 Dec 2022]

    Excited states of zero seniority based on a pair condensate

    Th. Popa · N. Sandulescu · M. Sambataro

    We study the excited states of zero seniority for various like-particle systems interacting by pairing forces and by general two-body interactions. We consider two types of excitations, generated from a ground state described by a pair condensate. One type is obtained by breaking a pair from the ground state condensate and replacing it by "excited" collective pairs built on time-reversed single-particle orbits. The second type of zero seniority excited states is described by a condensate of identical excited pairs. The structure of these excited states is analysed for the picked fence model and for the valence neutrons of Sn. For a state-depending pairing interaction, the first type of excited states agree well with the J=0 states which are known in Sn. At the same time, these states can be also associated unambiguously with those exact states which are the closest in energy to the experimental levels. The states corresponding to the excited pair condensate appear at low energies, around the energy of the second excited state of the first type, and they do not have a simple correspondence with exact eigenstates. However, at a much higher excitation energy there is an exact state which is similar in structure to an EPC state. It is shown that this EPC state has the features of a giant pairing vibration.

    Comments:
    22 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2212.08919 [pdf]
    PRC(2023)·2 citations
  3. 03

    [Submitted on 17 Dec 2022]

    Consideration of memory of spin and parity in the fissioning compound nucleus by applying the Hauser-Feshbach fission fragment decay model to photonuclear reactions

    Toshihiko Kawano · Amy E. Lovell · Shin Okumura · Hirokazu Sasaki · Ionel Stetcu · Patrick Talou

    Prompt and -delayed fission observables, such as the average number of prompt and delayed neutrons, the independent and cumulative fission product yields, and the prompt -ray energy spectra for the photonuclear reactions on U and Pu are calculated with the Hauser-Feshbach Fission Fragment Decay (HFD) model and compared with available experimental data. In the analysis of neutron-induced fission reactions to the case of photo-induced fission, an excellent reproduction of the delayed neutron yields supports a traditional assumption that the photo-fission might be similar to the neutron-induced fission at the same excitation energies regardless of the spin and parity of the fissioning systems.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2212.08943 [pdf]
    PRC(2023)·4 citations
  4. 04

    [Submitted on 19 Dec 2022]

    Temperature dependence of cluster decay

    D. F. Rojas-Gamboa · N. G. Kelkar · O. L. Caballero

    A universal decay law (UDL) for light cluster decay of excited nuclei is formulated by fitting the UDL half-lives to those evaluated within an excitation energy-dependent double folding model (DFM). The half-lives are evaluated within a preformed cluster model. The excitation energy dependence is introduced both in the energy of the emitted cluster and in the interaction potential through the density distributions of the interacting nuclei. The half-lives are found to decrease when the difference between the excitation energies of the parent and daughter nuclei, 0, increases, with the reduction being a few orders of magnitude for higher values of . This can be of importance for nucleosynthesis calculations of heavy elements formed in extremely hot environments, as well as in highly energetic heavy-ion collisions. The UDL for excited nuclei is used to provide an estimate of the enhancement in the cluster decay rates of thermally excited nuclei such as those produced in r-process nucleosynthesis.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2212.09221 [pdf]
    NPA(2022)·2 citations
  5. 05

    [Submitted on 19 Dec 2022]

    A Powerful New Energy Density Functional

    Anthony W Thomas🇦🇺 · Pierre A M Guichon🇫🇷 · Jesper Leong🇦🇺 · K L Martinez-Paglinawan · J R Stone🇬🇧

    We describe the most recent energy density functional derived within the quark meson coupling model. Although fit to the binding energies and charge radii of just seventy magic nuclei, the accuracy with which it reproduces nuclear properties across the entire periodic table is outstanding. As well as outlining a number of those results, we present an argument explaining why having a physically motivated model with a small number of parameters is especially desirable as one seeks to make predictions in new regions of N and Z. As an example we show the predictions for known super-heavy nuclei that were not included in the fit.

    Comments:
    Contribution to INPC2022
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2212.09228 [pdf]
    J.Phys.Conf.Ser.(2023)·2 citations
  6. 06

    [Submitted on 19 Dec 2022]

    Strong magnetic fields and pasta phases revisited

    Luigi Scurto🇵🇹 · Helena Pais🇪🇸 · Francesca Gulminelli🇫🇷

    In this work, we compute the structure and composition of the inner crust of a neutron star in the presence of a strong magnetic field, such as it can be found in magnetars. To determine the geometry and characteristics of the crust inhomogeneities, we consider the compressible liquid drop model, where surface and Coulomb terms are included in the variational equations, and we compare our results with previous calculations based on more approximate treatments. For the equation of state (EoS), we consider two non-linear relativistic mean-field models with different slopes of the symmetry energy, and we show that the extension of the inhomogeneous region inside the star core due to the magnetic field strongly depends on the behavior of the symmetry energy in the crustal EoS. Finally, we argue that the extended spinodal instability observed in previous calculations can be related to the presence of small amplitude density fluctuations in the magnetar outer core, rather than to a thicker solid crust. The compressible liquid drop model formalism, while in overall agreement with the previous calculations, leads to a systematic suppression of the metastable solutions, thus allowing a more precise estimation of the crust-core transition density and pressure, and therefore a better estimation of the crustal radius.

    Comments:
    11 pages, 5 figures, 3 tables. Version published on Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2212.09355 [pdf]
    PRC(2023)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE