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Nuclear Theory·nucl-th

Wednesday·May 15, 2024

16 papers—5 primary·11 cross-listed

All16Primary5Cross-lists11
  1. 01

    [Submitted on 13 May 2024]

    Relativistic Guiding-Center Motion: Action Principle, Kinetic Theory, and Hydrodynamics

    Dam Thanh Son · Mikhail Stephanov

    We treat the guiding-center dynamics in a varying external Maxwell field using a relativistically covariant action principle which reproduces the known Vandervoort expression for the drift velocity and extends it to curved spacetime. We derive the corresponding kinetic theory and ideal hydrodynamic theory. In contrast to conventional five-equation hydrodynamics, the guiding-center hydrodynamics needs only three equations due to a constraint on the motion across magnetic field. We argue that such a hydrodynamics is applicable to strongly coupled plasmas where kinetic theory fails.

    Comments:
    6 pages + 7 pages of supplementary material. Published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Theory (hep-th); Plasma Physics (physics.plasm-ph)
    arXiv:
    2405.08073 [pdf]
    PRL(2024)·2 citations
  2. 02

    [Submitted on 13 May 2024]

    Possible explanation of the irregular energy dependence of the rapidity width of mesons observed in Pb+Pb collisions

    Tom Reichert🇩🇪 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪

    Experimental data from the NA49 collaboration show an unexpectedly steep rise of the rapidity width of the meson as function of beam energy, which was suggested as possible interesting signal for novel physics. In this work we show that the Ultra-relativistic Quantum-Molecular-Dynamics (UrQMD) model is able to reproduce the shapes of the rapidity distributions of most measured hadrons and predicts a common linear increase of the width for all hadrons. Only when following the exact same analysis technique and experimental acceptance of the NA49 and NA61/SHINE collaborations, we find that the extracted value of the rapidity width of the increases drastically for the highest beam energy. We conclude that the observed steep increase of the rapidity width is a problem of limited detector acceptance and the simplified Gaussian fit approximation.

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2405.08094 [pdf]
    EPJA(2025)·0 citations
  3. 03

    [Submitted on 13 May 2024]

    Production cross sections of superheavy elements: insights from the dinuclear system model with high-quality microscopic nuclear masses

    Peng-Hui Chen · Chang Geng · Fei Niu · Zu-Xing Yang · Xiang-Hua Zeng · Zhao-Qing Feng

    To accurately predict the synthesis cross-sections of superheavy elements, identifying the optimal projectile-target combinations and the evaporation channels at specific collision energies, we have attempted to utilize high-quality microscopic nuclear masses (HQMNM) within the dinuclear system (DNS) model, which are obtained by fitting experimental data with the Skyrme energy density functional theory (DFT), as published in Phys. Lett. B 851 (2024) 138578. The atomic nuclear mass serves as a crucial input for the DNS model, as the Q-values and separation energies it generates directly influence the calculated fusion and survival probabilities. Our calculations have reproduced the experimental data for hot fusion and have been compared with results based on the finite-range droplet model (FRDM12) mass calculations. Compared to the FRDM12 mass results, we have found that the HQMNM provides a better fit to the experimental outcomes. For the specific reaction of \(^{48}\rm{Ca} + ^{243}\rm{Am} \rightarrow ^{291}\rm{Mc}^*\), we have conducted a detailed calculation of capture, fusion, and survival based on the HQMNM model and compared these with calculations based on other mass models. Based on these findings, we have systematically calculated available projectile target combinations for the synthesis of elements 119 and 120, and identified the optimal combinations. We provided the synthesis cross-sections, collision energies, and evaporation channels, offering a reference for conducting experiments on the synthesis of superheavy elements.

    Comments:
    8 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2405.08098 [pdf]
    0 citations
  4. 04

    [Submitted on 14 May 2024]

    Microscopic investigation of wobbling motion in atomic nuclei using the triaxial projected shell model approach

    J.A. Sheikh · S. Jehangir · G. H. Bhat

    A systematic investigation of the wobbling band structures observed in odd-mass nuclei of Lu, Ta Cs, Pr, Eu, Au, Ba, Pd, La, Au and Xe is performed using the triaxial projected shell model (TPSM) approach. It is demonstrated that all the studied band structures have transverse wobbling mode, except for La, Au (negative parity), Au (positive parity) and Xe nuclei where the wobbling frequency increases with spin, indicating that the collective motion has a longitudinal character. To elucidate further the wobbling nature of the band structures, electromagnetic transition probabilities have been evaluated and it is observed that inter-band transitions are dominated by rather than as expected for a typical signature partner band. It is shown that TPSM approach provides a reasonable description of all the measured properties of the studied nuclei.

    Comments:
    Version of the submitted version on arxiv to be published as chapter 12 of the book titled "Chirality and wobbling in Nuclei" by Taylor & Francis
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2405.08368 [pdf]
    0 citations
  5. 05

    [Submitted on 14 May 2024]

    Longitudinal structure of the quark-gluon plasma from differently shaped nuclei

    Jiangyong Jia🇺🇸 · Chunjian Zhang🇺🇸 · Shengli Huang🇺🇸

    Ultrarelativistic collisions of atomic nuclei produce the quark--gluon plasma (QGP), an extremely hot, dense state of matter. The QGP behaves like a nearly perfect fluid, so its final-state momentum distributions can be inverted to reveal its initial-state geometry. This programme has succeeded in the transverse plane but made less progress along the beam, where short-range nonflow correlations mask the longitudinal signal. Anisotropic flow has been successfully used to image the shapes of the colliding nuclei; here we use nuclear shape to image the QGP's 3D geometry---the same idea in reverse. We show in simulations that the nonflow can be removed by comparing collisions of nuclei with similar masses but different shapes. We find that nuclear deformation changes the magnitude of the elliptic flow but not its longitudinal profile, so the shape difference recovers the full longitudinal structure. The predicted two-particle decorrelation map reveals both a highly non-linear rapidity dependence inaccessible to conventional observables, and an unquantified bias in standard flow measurements themselves. Our strategy extends to the longitudinal dependence of the QGP's triangularity and size. Nuclear shape thus becomes a tool for 3D imaging of the QGP and the quantum fluctuations of the nuclear wavefunctions that seed it.

    Comments:
    12 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2405.08749 [pdf]
    12 citations

Affiliations

first authorsco-authorsvia INSPIRE