{
  "annotation_id": "da38063a-732e-4bea-9c20-365391184f9c",
  "date_created": "2026-03-02T18:01:18.143000Z",
  "date_modified": "2026-03-02T18:01:18.143000Z",
  "file_hash": "591e1591fbdca731141a8c434b4310d0809276a8f0b0668bfe8601cc39508c91",
  "private": false,
  "record": {
    "abstract": "Antiprotonic helium, a neutral exotic three-body system consisting of a\nhelium nucleus, an electron and an antiproton, is being studied at the\nAntiproton Decelerator of CERN by the ASAUCSA collaboration. Using laser\nspectroscopy of the energy levels of the antiproton in this system and\ncomparison to theory, a value of the antiproton-to-electron mass ratio with an\nerror of 3 ppb could be obtained. This result agrees with the most precise\nmeasurement of the value of the proton and allows us to extract a limit of the\nequality of the proton and antiproton charge and mass of 2 ppb. Using microwave\nspectroscopy, the hyperfine structure of antiprotonic helium has been measured\nto 30 ppm. Experimental improvements are expected to soon provide a new value\nfor the magnetic moment of the antiproton.",
    "arxiv_id": "physics/0703127",
    "authors": [
      "Eberhard Widmann"
    ],
    "categories": [
      "physics.atom-ph"
    ],
    "title": "Precision spectroscopy of antiprotonic helium",
    "url": "https://arxiv.org/abs/physics/0703127"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "de463dba-023a-47ff-bf30-013aaf52048a",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}