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Nuclear Theory·nucl-th

Friday·March 15, 2024

9 papers—3 primary·6 cross-listed

All9Primary3Cross-lists6
  1. 01

    [Submitted on 14 Mar 2024]

    Effects of neck and nuclear orientations on the mass drift in heavy ion collisions

    Shota Amano · Yoshihiro Aritomo · Masahisa Ohta

    We clarified that the fusion hindrance in heavy ion collisions is caused by the expansion of the neck bridge at the early stage of collision [Phys. Rev. C 108, 014612 (2023)]; however, our discussion was limited to the trajectory analysis. To get a reliable fusion cross section, it is important to understand the fusion process connecting with multinucleon transfer and also the process depending on the target orientation in detail. Especially, the effects of target orientation on the multinucleon transfer process have not been discussed so far in our model. First, we investigate precisely the start time of the neck expansion relevant to the mass transfer. The main aims of this paper are to discuss the mass drift in the collision with the different target orientations within the dynamical approach in the reaction 32S + 232Th. The orientation effects are incorporated within the framework of the Langevin equation. The start time of the neck expansion was presumed to be 10 zs by analysis in several entrance channels. By taking account of the target nuclear orientation, a strong mass-angle correlation was obtained which is compatible with the experimental data. Not only ``delayed relaxation'' of the neck but also the nuclear orientation effects have an important role in the strong correlation between fragment mass and its emitting angle. The mass evolution toward mass symmetry is slower than the standard mass drift mode assuming an exponential-type function. Particularly, the mass drift of the tip collision follows the slow mass drift mode assuming a Fermi-type function rather than an exponential-type function, which is related to the different features of the maximum neck cross-sectional area in the sticking process.

    Comments:
    Published in PRC on 11 March 2024. 13 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2403.09106 [pdf]
    PRC(2024)·3 citations
  2. 02

    [Submitted on 14 Mar 2024]

    Femtoscopic study of the interaction

    Asanosuke Jinno🇯🇵 · Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵 · Akira Ohnishi🇯🇵

    We examine the - () momentum correlation in high-energy collisions to elucidate the interaction between Lambdas () and nucleons (). We compare phenomenological potentials with different strengths at short range. In addition to the conventional Gaussian-type potentials, we construct the potentials by substituting the nucleon density distribution in into the Skyrme-type potentials. We find that the dependence on the employed potential models is visible in the correlation functions from a small-size source. This indicates that the momentum correlation could constrain the property of the interaction at high densities, which is expected to play an essential role in dense nuclear matter. Also, we verify that the Lednicky-Lyuboshits formula can yield erroneous results for a small-size source with a potential which has a large interaction range, like the system.

    Comments:
    8 pages, 6 figures, Published version in PRC, typos are fixed
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2403.09126 [pdf]
    PRC(2024)·15 citations
  3. 03

    [Submitted on 14 Mar 2024]

    Detecting the third family of compact stars with normalizing flows

    Valéria Carvalho🇵🇹 · Márcio Ferreira🇵🇹 · Constança Providência🇵🇹 · Michał Bejger🇵🇱

    We explore the anomaly detection framework based on Normalizing Flows (NF) models introduced in \cite{PhysRevC.106.065802} to detect the presence of a large (destabilising) dense matter phase transition in neutron star (NS) observations of masses and radii, and relate the feasibility of detection with parameters of the underlying mass-radius sequence, which is a functional of the dense matter equation of state. Once trained on simulated data featuring continuous solutions (i.e., no phase transitions), NF is used to determine the likelihood of a first-order phase transition in a given set of observations featuring a discontinuity, i.e., perform the anomaly detection. Different mock test sets, featuring two branch solutions in the diagram, were parameterized by the NS mass at which the phase transition occurs, , and the radius difference between the heaviest hadronic star and lightest hybrid star, . We analyze the impact of these parameters on the NF performance in detecting the presence of a first-order phase transition. Among the results, we report that given a set of 15 stars with radius uncertainty of km, a detection of a two-branch solution is possible with 95\% accuracy if km.

    Comments:
    9 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2403.09398 [pdf]
    PRD(2024)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE