{
  "abstract": "In a scalar effective field theory (EFT) with Galileon symmetry, we distinguish the strong-field expansion from the derivative expansion and study spherically symmetric classical nonlinear dynamics. More concretely, we consider two models related via perturbative field redefinitions: one with second-order equations that can also exhibit screening, and one that includes a higher-derivative term that introduces a propagating ghost. The latter term is of the type that can ``regularise'' the equations to render them well-posed as an initial value problem. For initial data that respect the derivative expansion, we find that the first model (ghost-free, unregularised) develops ill-posed regions during evolution only when the derivative expansion breaks down. This result persists in the strong-field regime. We further find that the regularized model reproduces the evolution of the unregularised one when the latter remains well-posed, while it exhibits tachyonic behaviour when the unregularised one becomes ill-posed. We also consider initial data that corresponds to stationary states that exhibit screening in the unregularised, ghost-free theory. In this case, we find that the regularised theory can remain well-posed for initial data that the unregularised one developed ill-posed regions. However, the ghost term naturally dominates over the Galileon term in the screening regime, contrary to common expectation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.05407",
  "author_total": 4,
  "authors": [
    {
      "name": "Farid Thaalba"
    },
    {
      "name": "Aaron Held"
    },
    {
      "name": "Ramiro Cayuso"
    },
    {
      "name": "Thomas P Sotiriou"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f6bkdnexv4df0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.05407",
  "fulltext_url": null,
  "id": "f6bkdnexv4df0",
  "issns": [],
  "landing_url": "https://hal.science/hal-05760382v1",
  "language": "en",
  "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",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "hal",
      "0.phys"
    ],
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      "hal",
      "1.phys.grqc"
    ],
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      "hal",
      "1.phys.hthe"
    ],
    [
      "openalex",
      "3103|Cosmology and Gravitation Theories"
    ]
  ],
  "openalex": "W7211876904",
  "pdf_url": "https://arxiv.org/pdf/2609.05407",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f6bkdnexv4df0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:39Z",
      "native_id": "hal-05760382",
      "source": "hal",
      "url": "https://hal.science/hal-05760382v1"
    },
    {
      "first_seen": "2026-10-30T12:19:14Z",
      "native_id": "2609.05407",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.05407"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-th",
      "subfield": "high-energy"
    }
  ],
  "title": "Nonlinear evolution in Galileon EFTs: Regularization and screening",
  "title_text": "Nonlinear evolution in Galileon EFTs: Regularization and screening",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:14Z",
  "url": "https://research.draconitic.com/paper/f6bkdnexv4df0",
  "venue": "HAL",
  "versions": []
}