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Nuclear Theory·nucl-th

Friday·October 13, 2023

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 7 Oct 2023]

    Role of isospin composition in low energy nuclear fusion

    Richard Gumbel · Christian Ross · A.S. Umar

    We employ a microscopic approach that examines the impact of isospin dynamics on the process of low energy nuclear fusion along an isotope chain and dependence on deformation. Our method utilizes the density constrained time-dependent Hartree-Fock theory (DC-TDHF), where isoscalar and isovector characteristics of the energy density functional (EDF) are examined in turn. This approach is applied to a series of fusion interactions of Yb with increasingly neutron rich isotopes of Calcium. By evaluating the contributions from the isoscalar and isovector components of the EDF, we look to quantify the influence of isospin composition on the conditions under which fusion is most likely to take place. Our findings reveal that, in non-symmetric systems, the isovector dynamics play a significant role. It's typical effect is a reduction in the potential barrier, which turns into enhancement for neutron-rich systems.

    Comments:
    5 pages, 6 figures. To be published in PRC
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2310.07734 [pdf]
    PRC(2023)·7 citations
  2. 02

    [Submitted on 12 Oct 2023]

    Semi-relativistic antisymmetrized molecular dynamics for energetic neutron production in intermediate energy heavy-ion reactions

    Q. Hu · G.Y. Tian · R. Wada · X.Q. Liu · W.P. Lin · H. Zheng · Y.P. Zhang · Z.Q. Chen · R. Han · M.R. Huang

    Relativistic corrections have been made in the non-relativistic antisymmetrized molecular dynamics (AMD) simulations to apply to the high energy neutron production in the C+C and O+C collisions at incident energies of 290 and 400 MeV/nucleon. The corrections are made in kinematics alone and no nucleon-nucleon inelastic scatterings nor meson productions are taken into account, and AMD with the relativistic corrections is called semi-relativistic AMD. The three-nucleon collision (3NC) and Fermi boost in the collision processes are taken into account in the non-relativistic AMD. Since the relativistic corrections tend to compensate in each other, the difference between the semi-relativistic and non-relativistic results become small. High energy tails of the available experimental neutron double differential cross sections, especially at larger angles, are well reproduced by AMD with the 3NC term both with non-relativistic and semi-relativistic simulations. These results indicate that the high energy neutrons are dominantly produced by the 3NC process in this incident energy range.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2310.08149 [pdf]
    PRC(2023)·1 citation
  3. 03

    [Submitted on 11 Oct 2023] (cross-list from hep-ph)

    Light quark mass dependence of nucleon electromagnetic form factors in dispersively modified chiral perturbation theory

    Fernando Alvarado🇪🇸 · Di An🇸🇪 · Luis Alvarez-Ruso🇪🇸 · Stefan Leupold🇸🇪

    The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and (1232) with dispersion theory. We specifically address the light-quark mass dependence of the form factors, achieving a good description of recent Lattice QCD results over a range of GeV and MeV. For the Dirac form factor, the combination of ChPT and dispersion theory outperforms the pure dispersive and pure ChPT descriptions. For the Pauli form factor, the combined calculation leads to results comparable to the purely dispersive ones. The anomalous magnetic moment and the Dirac and Pauli radii are extracted.

    Comments:
    27 pages, 13 figures. It contains supplementary material "anc"
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2310.07796 [pdf]
    PRD(2023)·12 citations
  4. 04

    [Submitted on 12 Oct 2023] (cross-list from hep-lat)

    Lattice real-time simulations with learned optimal kernels

    Daniel Alvestad🇳🇴 · Alexander Rothkopf🇳🇴 · Dénes Sexty🇦🇹

    We present a simulation strategy for the real-time dynamics of quantum fields, inspired by reinforcement learning. It builds on the complex Langevin approach, which it amends with system specific prior information, a necessary prerequisite to overcome this exceptionally severe sign problem. The optimization process underlying our machine learning approach is made possible by deploying inherently stable solvers of the complex Langevin stochastic process and a novel optimality criterion derived from insight into so-called boundary terms. This conceptual and technical progress allows us to both significantly extend the range of real-time simulations in 1+1d scalar field theory beyond the state-of-the-art and to avoid discretization artifacts that plagued previous real-time field theory simulations. Limitations of and promising future directions are discussed.

    Comments:
    5 pages, 5 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); cond-mat.other (cond-mat.other); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Machine Learning (stat.ML)
    arXiv:
    2310.08053 [pdf]
    PRD(2024)·26 citations
  5. 05

    [Submitted on 12 Oct 2023] (cross-list from hep-lat)

    Gravitational form factors of the proton from lattice QCD

    Daniel C. Hackett🇺🇸 · Dimitra A. Pefkou🇺🇸 · Phiala E. Shanahan🇺🇸

    The gravitational form factors (GFFs) of a hadron encode fundamental aspects of its structure, including its shape and size as defined from e.g., its energy density. This work presents a determination of the flavor decomposition of the GFFs of the proton from lattice QCD, in the kinematic region . The decomposition into up-, down-, strange-quark, and gluon contributions provides first-principles constraints on the role of each constituent in generating key proton structure observables, such as its mechanical radius, mass radius, and -term.

    Comments:
    Version published in PRL
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2310.08484 [pdf]
    PRL(2024)·154 citations

Affiliations

first authorsco-authorsvia INSPIRE