{
  "annotation_id": "c27506d9-2dd8-47da-98ec-db00e1b4e5c0",
  "date_created": "2026-02-17T05:53:19.548000Z",
  "date_modified": "2026-02-17T05:53:19.548000Z",
  "file_hash": "65f267334f6da6812efaaa3b82d83b2c75a3dc15d147e931b80f7c182381812d",
  "private": false,
  "record": {
    "abstract": "We investigate the quantum properties of heavy-fermion pairs, such as $t\\bar t$ or $\\tau^+\\tau^-$, produced in lepton-lepton collisions with polarised beams. Focusing on spin correlations, entanglement, Bell-inequality violation, and quantum-information--theoretic measures such as purity and magic, we analyse how beam polarisation shapes the structure of the spin-density matrix. We derive analytic expressions for a wide range of helicity configurations, including both Standard Model contributions and generic new-physics effects parametrised by scalar, vector, and tensor four-fermion operators within an effective field theory framework. We show that beam polarisation unlocks a substantially richer set of spin configurations and significantly enhances sensitivity to non-standard interactions. As a phenomenological application, we study $t\\bar t$ production at a future linear collider and demonstrate that quantum observables provide a comprehensive and complementary probe of top-quark interactions and stronger constraints on the scale of new physics.",
    "arxiv_id": "2601.09558",
    "authors": [
      "Mohammad Mahdi Altakach",
      "Priyanka Lamba",
      "Fabio Maltoni",
      "Kazuki Sakurai"
    ],
    "categories": [
      "hep-ph",
      "hep-ex",
      "hep-th",
      "quant-ph"
    ],
    "license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
    "title": "Quantum properties of heavy-fermion pairs at a lepton collider with polarised beams",
    "url": "https://arxiv.org/abs/2601.09558",
    "version": "v1"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "2b6fe480-5219-4c77-b7a1-7986a82603c4",
    "id": "arXiv Dataset",
    "type": "Model",
    "variant": "snapshot-2026-01-17",
    "version": "0.1.0"
  },
  "user_id": 1000002
}