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Nuclear Theory·nucl-th

Monday·September 30, 2024

15 papers—3 primary·12 cross-listed

All15Primary3Cross-lists12
  1. 01

    [Submitted on 26 Sept 2024]

    An Evaluation Of The Possible Effect Of Tetra-neutron Production On Ternary Fission Yields

    H. Pais · G. Röpke · J. B. Natowitz

    In this work, we study the effect of including a resonant state of four neutrons in the low-density warm nuclear equation of state, using a relativistic mean-field formalism, where in-medium effects are considered. For that purpose, the abundances of 62 different clusters immersed in a gas of protons and neutrons, are calculated with and without the presence of this resonant tetraneutron state. Ternary fission experiments are environments where not only these clusters can be formed, but also where such thermodynamic conditions of low densities and moderate temperatures can be achieved. The calculated yields of isotopes with and without the tetraneutron included are then compared with experimentally observed ternary fission yields. While the results indicate that the tetraneutron has little effect on yields of other clusters under the existing ternary fission conditions, a possibly observable effect on yields of clusters emitted from the neck region in mid-peripheral heavy ion collisions is clearly suggested.

    Comments:
    8 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2409.18232 [pdf]
    0 citations
  2. 02

    [Submitted on 26 Sept 2024]

    Coupled-Cluster Calculations of Infinite Nuclear Matter in the Complete Basis Limit Using Bayesian Machine Learning

    Julie Butler · Morten Hjorth-Jensen · Gustav R. Jansen

    Infinite nuclear matter provides valuable insights into the behavior of nuclear systems and aids our understanding of atomic nuclei and large-scale stellar objects such as neutron stars. However, partly due to the large basis needed to converge the system's binding energy, size-extensive methods such as coupled-cluster theory struggle with long computational run times, even using the nation's largest high-performance computing facilities. This research introduces a novel approach to the problem. We propose using a machine learning method to predict the coupled-cluster energies of infinite matter systems in the complete basis limit, leveraging only data collected using smaller basis sets. This method promises to deliver high-accuracy results with significantly reduced run times. The sequential regression extrapolation (SRE) algorithm, based on Gaussian processes, was created to perform these extrapolations. By combining Bayesian machine learning with a unique method of formatting the training data, we can create a powerful extrapolator that can make accurate predictions given very little data. The SRE algorithm successfully predicted the CCD(T) energies for pure neutron matter across six densities near nuclear saturation density, with an average error of 0.0083 MeV/N. The algorithm achieved an average error of 0.038 MeV/A for symmetric nuclear matter. These predictions were made with a time savings of 83.8 node hours for pure neutron matter and 284 node hours for symmetric nuclear matter. Additionally, the symmetry energy at these six densities was predicted with an average error of 0.031 MeV/A and a total time savings of 368 node hours compared to the traditional converged coupled-cluster calculations performed without the SRE algorithm.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2409.18234 [pdf]
    0 citations
  3. 03

    [Submitted on 27 Sept 2024]

    Light hypernuclei studied with chiral hyperon-nucleon and hyperon-nucleon-nucleon forces

    Hoai Le🇩🇪 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪 · Andreas Nogga🇩🇪

    A study of light hypernuclei in chiral effective field theory is presented. For the first time chiral NN and NN three-body forces are included consistently. The calculations are performed within the no-core shell model. Results for the separation energies of the hypernuclei , /, , and are given. It is found that the experimental values can be fairly well reproduced once YNN three-body forces are taken into account.

    Comments:
    6 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2409.18577 [pdf]
    PRL(2025)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE