{
  "abstract": "Characterized by central density depletion, bubble nuclei represent an important class of exotic nuclear structures. Collective flow in the $^{40}$Ca+$^{9}$Be projectile fragmentation reaction at 140 MeV/u is investigated using the extended quantum molecular dynamics (EQMD) model with a parameter on of the isoscalar monopole excitation strength $\\varepsilon$. The projectile $^{40}Ca$ is initialized as a relaxed ten-$α$ cluster configuration exhibiting a bubble-like density distribution. The results reveal that increasing $\\varepsilon$ modifies the density distribution and the size of the depleted central region of bubble, producing pronounced changes in fragment yields and collective flow around $\\varepsilon\\approx0.5$. Below this value, heavy-fragment production plays a significant role, while the directed flow $v_1$ of protons and neutrons remains predominantly negative, indicating preferential emission toward the target side. Above $\\varepsilon\\approx0.5$, enhanced expansion of the central low-density region suppresses heavy residues and drives $v_1$ toward positive values. In contrast, preformed $α$ clusters show different responses, reflecting their origin in the initial cluster configuration rather than solely in secondary decay. At low excitation, the cluster flow exhibits a pronounced impact-parameter dependence, whereas stronger excitation weakens cluster binding and suppresses directional anisotropy, driving the flow close to zero. The rapidity slopes of the flow coefficients also vary systematically with $\\varepsilon$, tracing changes in emission anisotropy during expansion. These findings extend traditional static descriptions by probing the dynamical evolution of exotic structures in heavy-ion reactions and the contrasting collective-flow behavior of preformed clusters and single nucleons constitutes a sensitive dynamical probe of bubble-like structures.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.19632",
  "author_total": 5,
  "authors": [
    {
      "name": "Ge Ren"
    },
    {
      "name": "Chun-Wang Ma"
    },
    {
      "name": "Xi-Guang Cao"
    },
    {
      "name": "Kai-Xuan Cheng"
    },
    {
      "name": "Jie Pu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cx9a6d8803v9k.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.19632",
  "fulltext_url": null,
  "id": "cx9a6d8803v9k",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.19632",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "nucl-ex"
    ],
    [
      "arxiv",
      "nucl-th"
    ],
    [
      "openalex",
      "3106|Nuclear physics research studies"
    ]
  ],
  "openalex": "W7222072672",
  "pdf_url": "https://arxiv.org/pdf/2610.19632",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cx9a6d8803v9k.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.19632",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.19632"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:nucl-ex",
      "subfield": "nuclear"
    }
  ],
  "title": "Collective-flow signatures of bubble nuclei in intermediate-energy projectile fragmentation reactions",
  "title_text": "Collective-flow signatures of bubble nuclei in intermediate-energy projectile fragmentation reactions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/cx9a6d8803v9k",
  "venue": "arXiv",
  "versions": []
}