{
  "abstract": "Exact diagrammatic quantum Monte Carlo (DiagMC) results for the nearest-neighbor Hubbard model motivate a closer study of the pseudogap. Using the improved two-particle self-consistent approach (TPSC+), we analyze Energy (EDC) and Momentum Distribution Curves (MDC) simultaneously. We show that Fermi-liquid terminology breaks down in the pseudogap regime, requiring a distinction between true and false Fermi surfaces and zero-energy quasiparticle (ZEQ) lines. A false Fermi surface has a momentum-space spectral maximum but a frequency-space depression at zero energy, while a false ZEQ line violates the standard quasiparticle condition $\\partial Σ'(\\mathbf{k},ω)/\\partial ω|_{ω=0}<0$.The pseudogap is driven by critical thermal spin fluctuations, which occur in two dimensions because of the Mermin-Wagner theorem. Commensurate fluctuations first open an antinodal pseudogap, leaving true Fermi arcs. With decreasing temperature, the Fermi surface evolves into hole- and electron-like false Fermi surfaces. Incommensurate fluctuations generate hot spots near the diagonal, where the pseudogap persists to the quantum critical point (QCP), whereas at $\\mathbf{k}_{AN}$ it disappears before the QCP doping. There, the spectrum has two precursor antiferromagnetic (AFM) bands, both in the unoccupied ($ω>0$) region. We benchmark TPSC+ against DiagMC results for the Matsubara spectral proxy $-\\mathrm{Im}[\\mathcal{G}(\\mathbf{k},iπT)]/π$. TPSC+ underestimates pseudogap suppression in the strong-interaction regime, reproducing DiagMC behavior at lower temperatures or doping. This proxy is equivalent to the spectral function with thermal broadening $η=πT$, which obscures features when $πT$ is not the smallest energy scale. Using $A(\\mathbf{k},0)$, we find that hole-like Fermi surfaces emerge at any interaction strength at low temperature, even at weak coupling.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.12339",
  "author_total": 1,
  "authors": [
    {
      "name": "Y. M. Vilk"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1bf3wrbran94d.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.12339",
  "fulltext_url": null,
  "id": "1bf3wrbran94d",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.12339",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.str-el"
    ],
    [
      "openalex",
      "3104|Physics of Superconductivity and Magnetism"
    ]
  ],
  "openalex": "W7221119370",
  "pdf_url": "https://arxiv.org/pdf/2610.12339",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1bf3wrbran94d.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:54Z",
      "native_id": "2610.12339",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.12339"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.str-el",
      "subfield": "condensed-matter"
    }
  ],
  "title": "True vs false Fermi surfaces in the Pseudogap regime and their transformation with doping and temperature in the Hubbard Model",
  "title_text": "True vs false Fermi surfaces in the Pseudogap regime and their transformation with doping and temperature in the Hubbard Model",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:54Z",
  "url": "https://research.draconitic.com/paper/1bf3wrbran94d",
  "venue": "arXiv",
  "versions": []
}