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Nuclear Theory·nucl-th

Friday·December 1, 2023

11 papers—3 primary·8 cross-listed

All11Primary3Cross-lists8
  1. 01

    [Submitted on 30 Nov 2023]

    Evolution of giant monopole resonance with triaxial deformation

    Kouhei Washiyama · Shuichiro Ebata · Kenichi Yoshida

    Background: The isoscalar giant monopole resonance (ISGMR) splits into two peaks in prolately deformed nuclei. When a nucleus is triaxially deformed, a peak appears in the middle between the two peaks. Purpose: We investigate the mechanism of the appearance of the middle peak in the ISGMR in triaxial nuclei. Method: We perform the constrained Skyrme-Hartree-Fock-Bogoliubov (CHFB) calculation for arbitrary triaxial shapes in Mo. We calculate the strength functions of the isoscalar monopole (ISM) and IS quadrupole modes on the CHFB states. Furthermore, we investigate vibrations of matter distributions in , , and directions induced by the external ISM field, with the axis being the longest axis of the triaxial shape. Results: The middle peak in the ISM strength evolves from the triaxial degree to . This is because the difference between the vibration in direction and that in direction is evident with an increase in and the quadrupole component of the induced density of the ISM at the middle peak increases as increases, where denotes the component of the angular momentum. This property is also obtained in the unperturbed ISM strength without the residual fields. Conclusions: The mixing between the monopole and quadrupole modes is primarily determined by the ground-state deformation. Therefore, the ISM strength of the middle peak becomes strong as the triaxial degree in the ground state increases.

    Comments:
    7 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2311.18317 [pdf]
    PRC(2024)·2 citations
  2. 02

    [Submitted on 30 Nov 2023]

    Scaling behaviour of in high-energy collisions

    Gábor Kasza🇭🇺 · Tamás Csörgő🇭🇺

    From a recently found family of analytic, finite and accelerating 1+1-dimensional solutions to perfect fluid relativistic hydrodynamics, we derive simple and powerful formulae to describe the rapidity and pseudorapidity density distributions. By introducing a new scaling function, we notice that the rapidity distribution data of the different experiments all collapse into a single curve. This data-collapsing (or scaling) behaviour in the rapidity distributions suggests that high-energy collisions may be described as collective systems.

    Comments:
    10 pages, 2 figures. This paper is accepted for publication in MDPI Journal Universe
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2311.18678 [pdf]
    Universe(2024)·2 citations
  3. 03

    [Submitted on 30 Nov 2023]

    Structure in the speed of sound: from neutron stars to heavy-ion collisions

    Nanxi Yao🇺🇸 · Agnieszka Sorensen🇺🇸 · Veronica Dexheimer🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    From the observation of both heavy neutron stars and light ones with small radii, one anticipates a steep rise in the speed of sound of nuclear matter as a function of baryon density up to values close to the causal limit. A question follows whether such behavior of the speed of sound in neutron-rich matter is compatible with the equation of state extracted from low-energy heavy-ion collisions. In this work, we consider a family of neutron star equations of state characterized by a steep rise in the speed of sound, and use the symmetry energy expansion to obtain equations of state applicable to the almost-symmetric nuclear matter created in heavy-ion collisions. We then compare collective flow data from low-energy heavy-ion experiments with results of simulations obtained using the hadronic transport code SMASH with the mean-field potential reproducing the density-dependence of the speed of sound. We show that equations of state featuring a peak in the speed of sound squared occurring at densities between 2-3 times the saturation density of normal nuclear matter, producing neutron stars of nearly M_max~2.5 M_Sun, are consistent with heavy-ion collision data.

    Comments:
    Updated version for journal submission
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2311.18819 [pdf]
    PRC(2024)·44 citations

Affiliations

first authorsco-authorsvia INSPIRE