{
  "annotation_id": "7550218e-9cb8-4f78-910e-272896e438ff",
  "date_created": "2026-03-02T18:00:39.709000Z",
  "date_modified": "2026-03-02T18:00:39.709000Z",
  "file_hash": "b2d21930dcb82d9ed0335c833a12e38b9c741dd58243ba03e544cc6e5f4b3374",
  "private": false,
  "record": {
    "abstract": "Gouy\u0027s phase of transversally limited pulses can create a strong anomalous\ndispersion in vacuum leading to highly superluminal and negative group\nvelocities. As a consequence, a focusing pulse can diverge beyond the focus\nbefore converging into it. A simple experiment is proposed.",
    "arxiv_id": "physics/0202069",
    "authors": [
      "M. A. Porras",
      "I. Gonzalo",
      "A. Mondello"
    ],
    "categories": [
      "physics.optics",
      "physics.class-ph"
    ],
    "doi": "10.1103/PhysRevE.67.066604",
    "title": "Pulsed light beams in vacuum with superluminal and negative group   velocities",
    "url": "https://arxiv.org/abs/physics/0202069"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "0d689dd0-be96-4a06-a6e0-e92f4a57e7cd",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}