{
  "abstract": "The two-loop amplitudes for pseudoscalar pair production in gluon fusion, $gg\\to AA$, with each pseudoscalar emitted from its own effective gluon vertex, are known in closed form, but large cancellations near threshold obscure their analytic structure. We expand the IR-finite amplitudes in the pseudoscalar velocity $β_A$ through $β_A^6$ at fixed scattering angle. All inverse powers of $β_A$ and the odd powers through $β_A^5$ cancel, and at leading power the angular dependence enters only through $\\ln(2p_T/m_A)$. We identify this logarithm with the double parton scattering (DPS) singularity: with the overall constant fixed at threshold, the factorisation formula of Gaunt and Stirling reproduces the velocity dependence of its one-loop coefficient in the forward limit to $3\\times10^{-15}$, and a one-loop $gg\\to HH$ analysis confirms the corresponding CP-even weight. At two loops the equal-helicity amplitude grows as $\\ln^3p_T$, with the leading logarithmic ratio of planar $\\mathcal N=4$ super Yang-Mills theory, while the opposite helicity amplitude, which has no one-loop DPS logarithm, grows as $\\ln^2p_T$. In the finite virtual correction, relative to the squared tree amplitude, the highest logarithm at order $α_s^2$ is $-\\tfrac{7}{64}α_s^2N_c^2\\ln^2(2p_T/m_A)$. For $β_A\\leq0.2$ the series reproduce the unexpanded amplitudes with relative errors of at most $6.77\\times10^{-5}$ at the tested points; they provide this two-loop contribution to the hard function for soft-gluon resummation of the pair invariant-mass distribution near $m_{AA}=2m_A$ and are released with code for their numerical evaluation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.19024",
  "author_total": 1,
  "authors": [
    {
      "name": "Arunima Bhattacharya"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dkvg4emqh3kdc.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.19024",
  "fulltext_url": null,
  "id": "dkvg4emqh3kdc",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.19024",
  "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",
      "hep-ph"
    ],
    [
      "openalex",
      "3106|Particle physics theoretical and experimental studies"
    ]
  ],
  "openalex": "W7222271948",
  "pdf_url": "https://arxiv.org/pdf/2610.19024",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dkvg4emqh3kdc.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.19024",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.19024"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Two-loop $gg\\to AA$ amplitudes near threshold and the double parton scattering singularity",
  "title_text": "Two-loop gg→ AA amplitudes near threshold and the double parton scattering singularity",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:31Z",
  "url": "https://research.draconitic.com/paper/dkvg4emqh3kdc",
  "venue": "arXiv",
  "versions": []
}