{
  "abstract": "We investigate whether early- and late-time dark energy could arise from a single scalar field. Adopting a bottom-up perspective, we first identify the sequence of dynamical regimes that any unified scenario must traverse to account for both an early dark energy phase relevant for pre-recombination solutions of the Hubble tension and the late-time acceleration of the Universe. We derive the corresponding requirements on the scalar energy density and equation of state. We then adopt a complementary top-down perspective and translate these requirements into constraints on the phase-space structure of minimally coupled scalar fields with tracking-like dynamics. We show that satisfying all requirements necessitates a potential with three distinct slopes, arranged in a steep-steeper-shallow hierarchy. This conclusion remains unchanged in the presence of conformal couplings to dark matter. These results place strong constraints on attempts to construct unified models of early- and late-time dark energy. We discuss implications for model-building.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2605.26116",
  "author_total": 2,
  "authors": [
    {
      "name": "William Giarè"
    },
    {
      "name": "Jeremy Sakstein"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f8yrbjvqm04dq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2605.26116",
  "fulltext_url": null,
  "id": "f8yrbjvqm04dq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2605.26116",
  "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",
      "astro-ph.CO"
    ],
    [
      "arxiv",
      "gr-qc"
    ],
    [
      "arxiv",
      "hep-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2605.26116",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f8yrbjvqm04dq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:11Z",
      "native_id": "2605.26116",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2605.26116"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.CO",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "arxiv:gr-qc",
      "subfield": "gravitation"
    },
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Unifying Early and Late Dark Energy: Dynamical Requirements and Obstructions",
  "title_text": "Unifying Early and Late Dark Energy: Dynamical Requirements and Obstructions",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:11Z",
  "url": "https://research.draconitic.com/paper/f8yrbjvqm04dq",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1088/1475-7516/2026/09/096",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}