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Nuclear Theory·nucl-th

Thursday·May 2, 2024

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    [Submitted on 1 May 2024]

    Study of proton-proton Scattering using Phase Function Method

    Shikha Awasthi · Anil Khachi · O.S.K.S. Sastri

    Background: The study of np and pp scattering, central to understanding nuclear force, remains an optional topic in many undergraduate nuclear physics curriculum. Purpose: The main thrust of this paper is to study pp scattering using the phase function method to obtain the observed S-wave phase shifts and cross-sections at various energies. Methods: The pp interaction has been modeled by choosing the Malfliet-Tjon potential for the nuclear part along with the screened Coulomb potential. The phase equation has been solved to obtain scattering phase shifts using the fourth-order RK method (RK-4). Results: The interaction potential obtained from optimized parameters matches well with the realistic Argonne V18 potential for 1S0 state of pp scattering and the scattering phase shifts as well as the cross-section for energies ranging from 1-350 MeV are in good agreement with expected data. Conclusion: Introducing the phase function method for S-wave (l=0) could bring this interesting study of nucleon-nucleon scattering to the undergraduate classroom.

    Comments:
    18, 5 Figures, 2 Tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2405.00310 [pdf]
    0 citations
  2. 02

    [Submitted on 1 May 2024]

    Nuclear mass predictions with anisotropic kernel ridge regression

    X. H. Wu · C. Pan

    The anisotropic kernel ridge regression (AKRR) approach in nuclear mass predictions is developed by introducing the anisotropic kernel function into the kernel ridge regression (KRR) approach, without introducing new weight parameter or input in the training. A combination of double two-dimensional Gaussian kernel function is adopted, and the corresponding hyperparameters are optimized carefully by cross-validations. The anisotropic kernel shows cross-shape pattern, which highlights the correlations among the isotopes with the same proton number, and that among the isotones with the same neutron number. Significant improvements are achieved by the AKRR approach in both the interpolation and the extrapolation predictions of nuclear masses comparing with the original KRR approach.

    Comments:
    7 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2405.00356 [pdf]
    PRC(2024)·16 citations
  3. 03

    [Submitted on 1 May 2024]

    Particle production from gluon-nucleon interactions in relativistic heavy ion collisions

    Yong-Ping Fu🇨🇳 · Fei-Jie Huang🇨🇳 · Qi-Hui Chen🇨🇳

    We propose a particle production mechanism analogous to the particle photoproduction processes, arising from the gluon-nucleon interactions in relativistic heavy ion collisions. The comparison is made on the effect of the gluon-nucleon interactions on the photon production in Au+Au collisions at 200 GeV and Pb+Pb collisions at 2.76 TeV. The numerical results indicate that as the collision energy increases, the contribution of gluon-nucleon interactions becomes more prominent.

    Comments:
    6 pages,7 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2405.00396 [pdf]
    0 citations
  4. 04

    [Submitted on 1 May 2024]

    Damping of spin waves

    David Wagner🇩🇪 · Masoud Shokri🇩🇪 · Dirk H. Rischke🇩🇪

    We show that, in ideal-spin hydrodynamics, the components of the spin tensor follow damped wave equations. The damping rate is related to nonlocal collisions of the particles in the fluid, which enter at first order in in a semi-classical expansion. This rate provides an estimate for the timescale of spin equilibration and is computed by considering a system of spin-1/2 fermions interacting via a quartic self-interaction as well as via (screened) one-gluon exchange. It is found that the relaxation times of the components of the spin tensor can become very large compared to the usual dissipative timescales of the system. Our results suggest that the spin degrees of freedom in a heavy-ion collision may not be in equilibrium by the time of freeze-out, and thus should be treated dynamically.

    Comments:
    13 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    2405.00533 [pdf]
    PRResearch(2024)·44 citations

Affiliations

first authorsco-authorsvia INSPIRE