{
  "abstract": "We extend a lattice-QCD determination of the response of the quark-gluon plasma to an external magnetic field using a Taylor expansion of the pressure at zero field. A zero-net-flux ``half-and-half'' magnetic-field configuration permits continuous differentiation with respect to the field amplitude on gauge ensembles generated at $B=0$. The electromagnetic vector potential is chosen to minimize stochastic noise in the Taylor operators. Previous results through $O(B^2)$ are extended to $O(B^4)$ using $2+1$-flavor HISQ/tree ensembles with $m_l/m_s=0.05$ and $N_t=8$. The renormalized quadratic coefficient confirms paramagnetic behavior above the QCD crossover. The fourth-order coefficient $C_4$ is small at high temperature and is enhanced near the crossover. At $T=167$ MeV the $C_4$ result at $48^3\\times 8$ lies about two standard deviations above the corresponding $32^3\\times8$ one, indicating likely finite- volume effects. For $eB = 0.2$ GeV$^2$, characteristic of magnetic fields relevant to heavy-ion phenomenology, the fourth-order contribution is small compared with the leading magnetic correction at moderate and high temperatures, but near the crossover the large-volume result is about half of the central value of the quadratic term, after the vacuum-pressure subtraction. We also place the method in the context of other lattice determinations of magnetic susceptibility and clarify the relevance of finite-volume effects for the thermal subtraction. This work was completed in 2014 and preliminary results were reported at Lattice 2014.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.37799",
  "author_total": 2,
  "authors": [
    {
      "name": "L. Levkova"
    },
    {
      "name": "C. DeTar"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/10djpa1dy3v10.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.37799",
  "fulltext_url": null,
  "id": "10djpa1dy3v10",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.37799",
  "language": null,
  "licence": "CC-BY-SA-4.0",
  "licence_label": "CC BY-SA 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-sa/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "hep-lat"
    ],
    [
      "arxiv",
      "hep-th"
    ],
    [
      "openalex",
      "3106|High-Energy Particle Collisions Research"
    ]
  ],
  "openalex": "W7214991627",
  "pdf_url": "https://arxiv.org/pdf/2609.37799",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-29",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/10djpa1dy3v10.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:31Z",
      "native_id": "2609.37799",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.37799"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-lat",
      "subfield": "high-energy"
    }
  ],
  "title": "Equation of State of the Quark-Gluon Plasma in an External Magnetic Field to Fourth Order",
  "title_text": "Equation of State of the Quark-Gluon Plasma in an External Magnetic Field to Fourth Order",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:31Z",
  "url": "https://research.draconitic.com/paper/10djpa1dy3v10",
  "venue": "arXiv",
  "versions": []
}