{
  "abstract": "In polar semiconductors the Fröhlich interaction is the dominant electron--phonon coupling, yet excitonic resonances in materials such as halide perovskites remain anomalously sharp. We show that standard frozen-center-of-mass treatments of the exciton--phonon problem miss the decisive kinematic degree of freedom: restoring the exact center-of-mass (COM) recoil reveals a universally open, parameter-free $1s\\to1s$ absorption channel at recoil momentum $q_*=\\sqrt{2M_{\\rm ex}\\hbarω_{\\rm LO}}/\\hbar$, whose rate scales as $N_{\\rm LO}(T)$. We prove that this recoil channel is controlled by destructive electron--hole interference: the recoil linewidth vanishes with the mass asymmetry as $γ_{\\rm LO}^{\\rm recoil}\\propto\\mathcal{F}_{1s,1s}(q_*)^2$, and the elastic dressing obeys the exact suppression law $S_X/S_{\\rm ind}=η^2(6-η^2)/5$ within the hydrogenic Fröhlich model. The theory establishes a hierarchy of scattering regimes. In mass-asymmetric materials (GaAs, $η=-0.74$) the recoil channel is active ($γ_{\\rm LO}^{\\rm recoil}=2.2$~meV); in mass-symmetric materials (FAPbI$_3$, $η=0$; MAPbI$_3$, $η=-0.11$) it is killed by interference (0.00 and 0.12 meV), showing that the observed 27--40 meV perovskite linewidths cannot be accounted for by COM recoil and therefore require internal-state-changing and other inelastic channels, of which the constructive, $η$-robust $1s\\to np$ resonance is the leading candidate within the present model. The Fröhlich constant $α$ alone is therefore insufficient as a figure of merit: after projection onto the correlated exciton, the controlling parameters are $η$, $q_*a_X$, and the Rydberg detuning.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.01600",
  "author_total": 1,
  "authors": [
    {
      "name": "Michael O. Atambo"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/dxrg6bzh3rk7h.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.01600",
  "fulltext_url": null,
  "id": "dxrg6bzh3rk7h",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.01600",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "cond-mat.str-el"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.01600",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/dxrg6bzh3rk7h.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:26:03Z",
      "native_id": "2610.01600",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.01600"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Why polar excitons stay sharp: parity protection of the center-of-mass recoil channel in exciton-phonon scattering",
  "title_text": "Why polar excitons stay sharp: parity protection of the center-of-mass recoil channel in exciton-phonon scattering",
  "type": "preprint",
  "updated_at": "2026-10-30T12:26:03Z",
  "url": "https://research.draconitic.com/paper/dxrg6bzh3rk7h",
  "venue": "arXiv",
  "versions": []
}