{
  "abstract": "We update our analyses concerning the non-resonant (Drell-Söding) contribution to the reaction $γ^{(*)} p \\to π^{+} π^{-} p$, now including general vertex functions for the coupling of pomeron, $f_{2 \\mathbb{R}}$, and $ρ_{\\mathbb{R}}$, to pions. This takes into account the off-shellness of the pions. We present a comparison of our tensor-pomeron model, including our new Drell-Söding and $ρ$, $ω$ vector-meson contributions, with data for the $γp \\to π^{+} π^{-} p$ reaction measured by the ZEUS and H1 Collaborations. We find very good agreement of our theory with the experimental data for the $π^{+} π^{-}$ invariant mass ($M_{ππ}$) and for angular distributions. Here we restrict our analysis to the region $M_{ππ} \\lesssim 1.2$ GeV. For higher values of $M_{ππ}$ we will have to consider production of higher-mass mesons. The purpose of the present article is to show that our tensor-pomeron model gives a very good fit to the so-called skewing of the $ρ$-resonance contribution in photoproduction. In fact, it is an old problem/puzzle to understood the difference of the shapes of the $M_{ππ}$ distributions in the region of the $ρ(770)$ resonance in $e^{+} e^{-}$ annihilation and photoproduction. We think that with our results we have obtained for this problem a solution which is very satisfactory from the Quantum-Field-Theory point of view. Our results are also relevant for central-exclusive $π^{+} π^{-}$ production in ultraperipheral $pp$, A$p$, and AA collisions at the LHC and for photo- and electroproduction of $π^{+} π^{-}$ at future electron-proton/ion colliders, EIC and LeHC.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.01285",
  "author_total": 3,
  "authors": [
    {
      "name": "Piotr Lebiedowicz"
    },
    {
      "name": "Otto Nachtmann"
    },
    {
      "name": "Antoni Szczurek"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bnmw2jwbv2q8t.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.01285",
  "fulltext_url": null,
  "id": "bnmw2jwbv2q8t",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.01285",
  "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-ph"
    ],
    [
      "openalex",
      "3106|Quantum Chromodynamics and Particle Interactions"
    ]
  ],
  "openalex": "W7206194753",
  "pdf_url": "https://arxiv.org/pdf/2609.01285",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bnmw2jwbv2q8t.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:00Z",
      "native_id": "2609.01285",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.01285"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:hep-ph",
      "subfield": "high-energy"
    }
  ],
  "title": "Addendum: Production of $π^{+} π^{-}$ pairs in diffractive photon-proton and in proton-proton collisions revisited, in particular concerning the Drell-Söding contribution",
  "title_text": "Addendum: Production of π^+ π^− pairs in diffractive photon-proton and in proton-proton collisions revisited, in particular concerning the Drell-Söding contribution",
  "type": "preprint",
  "updated_at": "2026-11-04T15:20:50Z",
  "url": "https://research.draconitic.com/paper/bnmw2jwbv2q8t",
  "venue": "arXiv",
  "versions": []
}