{
  "abstract": "We report precise results for the $e^+e^-\\to π^+π^-(γ)$ cross section in the energy range between threshold and 1.4 GeV, relevant for the hadronic vacuum polarization contribution to the muon $g-2$ prediction. Using the full 460 fb$^{-1}$ of on- and off-$Υ(4S)$ data, the cross section is derived from the ratio of $π^+π^-$ to $μ^+μ^-$ initial-state radiation (ISR) events, in which many systematic uncertainties cancel. The pion/muon separation does not rely on particle identification as in the 2009 BaBar analysis, but rather makes use of the well-known, different angular distributions in the two-particle center-of-mass system. The compatibility and correlation between the 2026 and 2009 measurements are discussed. The new measurement is also compared with other two-pion results. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the new 2026 and combined 2009 and 2026 BaBar measurements in the energy range of 0.3$-$1.4 GeV are $525.9\\pm 3.5_\\mathrm{stat}\\pm3.8_\\mathrm{syst}$ and $517.8\\pm 2.4_\\mathrm{stat}\\pm3.3_\\mathrm{syst}$ in units of $10^{-10}$, respectively.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.04621",
  "author_total": 1,
  "authors": [
    {
      "name": "BaBar Collaboration"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/aca00pm7advpe.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.04621",
  "fulltext_url": null,
  "id": "aca00pm7advpe",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.04621",
  "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-ex"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.04621",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-03",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/aca00pm7advpe.ris",
  "sources": [
    {
      "first_seen": "2026-11-04T15:21:25Z",
      "native_id": "2611.04621",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.04621"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ex",
      "subfield": "high-energy"
    }
  ],
  "title": "A New Precise Measurement of the $e^+e^-\\toπ^+π^-(γ)$ Cross Section with the Initial-State Radiation Method at BaBar",
  "title_text": "A New Precise Measurement of the e^+e^-→π^+π^-(γ) Cross Section with the Initial-State Radiation Method at BaBar",
  "type": "preprint",
  "updated_at": "2026-11-05T15:20:35Z",
  "url": "https://research.draconitic.com/paper/aca00pm7advpe",
  "venue": "arXiv",
  "versions": []
}