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Nuclear Theory·nucl-th

Wednesday·September 27, 2023

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 25 Sept 2023]

    Electron Dynamics in Neutron Scattering with Hydrogen Atoms

    Mingzhao Xing · Libin Fu

    In neutron-proton (n-p) scattering experiments, gas targets have been used to measure scattering length by detecting neutrons and recoil protons. Changes in electron dynamics within the gas target have a negligible effect on dynamics of neutrons and protons. However, electron dynamics are sensitive to the specific form of the n-p interaction during the scattering process, providing additional information to derive parameters in nuclear interaction models. We propose a theoretical approach to obtain these parameters from the momentum spectrum of ionized electrons within a hydrogen atomic gas target. This approach is based on a three-body scattering involving a neutron, a proton and an electron. We model the n-p interaction as the Yukawa potential and obtain the momentum spectrum of ionized electrons through the solution of the Time-Dependent Schrödinger Equation. Electron dynamics exhibit significant differences at various potential parameters. These parameters can be determined by comparing numerical calculations with experimental results. Moreover, this approach offers insights into detecting ultrafast scattering processes.

    Comments:
    15 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2309.14470 [pdf]
    Commun.Theor.Phys.(2025)·0 citations
  2. 02

    [Submitted on 25 Sept 2023]

    Be in the Cluster Shell Model

    Omar Alejandro Diaz Caballero · Roelof Bijker

    The Cluster Shell Model (CSM)describes light nuclei in terms of particles and extra nucleons, in which the extra nucleon move in the deformed field generated by the geometric configuration of -particles. We present the first study for the case nucleons in application to as a cluster of two -particles and two neutrons.

    Comments:
    5 pages, 3 figures, 1 table, to be published in Journal of Physics Conference Series
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2309.14505 [pdf]
    J.Phys.Conf.Ser.(2023)·1 citation
  3. 03

    [Submitted on 26 Sept 2023]

    Structure of C in the Cluster Shell Model

    Adrian Santana-Valdés · Roelof Bijker

    We study the structure of C in the framework of the Cluster Shell Model. A comparison of the available experimental data with our model is made. Some predictions for level ordering and form factors are presented.

    Comments:
    8 pages, 6 figures, to be published in Journal of Physics Conference Series
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2309.14588 [pdf]
    J.Phys.Conf.Ser.(2023)·1 citation
  4. 04

    [Submitted on 26 Sept 2023]

    Probing the existence of \eta^3He mesic nucleus with a few-body approach

    Qian Wu🇨🇳 · Gang Xie🇨🇳 · Xurong Chen🇨🇳

    Motivated by the two recent observations in the WASA-at-COSY detector, we investigate the He nucleus with the few body method. We construct the effective -wave energy dependent potential which reproduce the subthreshold scattering amplitude in the 2005 Green-Wycech model. It gives the separation energy and decay width of 0.19 MeV and 1.71 MeV, respectively. We also construct various sets of effective -wave energy independent potentials where the corresponding complex scattering lengths (a) are within the range given in most theoretical models. We obtain the bound He nucleus with decay width of about 5 MeV when a is (1.0 fm, 0.3 fm), and of about 10 MeV when a is (1.0 fm, 0.5 fm).

    Comments:
    7 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2309.14711 [pdf]
    PLB(2024)·1 citation
  5. 05

    [Submitted on 26 Sept 2023]

    The regime of applicability of Israel-Stewart hydrodynamics

    David Wagner · Lorenzo Gavassino

    Using analytical tools from linear response theory, we systematically assess the accuracy of several microscopic derivations of Israel-Stewart hydrodynamics near local equilibrium. This allows us to "rank" the different approaches in decreasing order of accuracy as follows: Inverse Reynolds Dominance (IReD), Denicol-Niemi-Molnár-Rischke (DNMR), second-order gradient expansion, and 14-moment approximation. We find that IReD theory is far superior to Navier-Stokes, being very accurate both in the asymptotic regime (i.e., for slow processes) and in the transient regime (i.e., on timescales comparable to the relaxation time). Also, the high accuracy of DNMR is confirmed, but neglecting second-order terms in the Knudsen number, which would render the equations parabolic, introduces serious systematic errors. Finally, in most cases, the second-order gradient expansion (a.k.a. non-resummed BRSSS) is found to be more inaccurate than Navier-Stokes in the transient regime. Overall, this analysis shows that Israel-Stewart hydrodynamics is falsifiable, and the relaxation time is observable, shedding new light on the debate on the viability of transient hydrodynamics as a well-defined physical theory distinguished from Navier-Stokes.

    Comments:
    21 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
    arXiv:
    2309.14828 [pdf]
    PRD(2024)·26 citations
  6. 06

    [Submitted on 26 Sept 2023]

    Comparison of optical models

    Jaume Carbonell🇫🇷 · Guillaume Hupin🇫🇷 · Sławomir Wycech🇵🇱

    We compare the strong part of the interaction obtained by the Nijmegen partial wave analysis and the results of some of the most popular optical potentials in configuration space. We have found severe discrepancies in most of the partial waves, especially above =400 MeV/c where the partial wave analysis displays a resonant-like structure in the S and P waves. Some theoretical difficulties to interpret this behaviour in terms of dynamical resonances are pointed pout and an alternative explanation is suggested. A much better stability is observed in the low energy parameters, apart from some discrepancies due to the presence of near-threshold quasi-bound states in particular waves. Large deviations have also been found between the corresponding potentials, at short and medium-range ( fm) distances.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Atomic Physics (physics.atom-ph)
    arXiv:
    2309.14831 [pdf]
    EPJA(2023)·12 citations
  7. 07

    [Submitted on 26 Sept 2023]

    Model for compound nucleus formation in various heavy-ion systems

    V. Yu. Denisov

    The statistical model for the calculation of the compound nucleus formation cross section and the probability of compound nucleus formation in heavy-ion collisions is discussed in detail. The light, heavy, and super-heavy nucleus-nucleus systems are considered in this model in the framework of one approach. It is shown that the compound nucleus is formed in competition between passing through the compound-nucleus formation barrier and the quasi-elastic barrier. The compound-nucleus formation barrier is the barrier separating the system of contacting incident nuclei and the spherical or near-spherical ground state of the compound nucleus. The quasi-elastic barrier is the barrier between the contacting and well-separated deformed ions. It is shown that the compound nucleus formation cross-section is suppressed when the quasi-elastic barrier is lower than the compound nucleus formation barrier. The critical value of angular momentum, which limits the compound nucleus formation cross-section values for light and medium ion-ion systems at over-barrier collision energies, is discussed in the model. The suppression of the compound nucleus formation cross-section even at small partial waves for very heavy ion-ion systems is obtained in the model. The values of the capture and compound nucleus formation cross-sections calculated for various light, heavy, and super-heavy nucleus-nucleus systems as well as the probability of the compound nucleus formation for super-heavy nuclei are well agreed with the available experimental data.

    Comments:
    17 pages, 6 figures, 2 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2309.14995 [pdf]
    PRC(2024)·3 citations

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first authorsco-authorsvia INSPIRE