{"paper":{"title":"Why is the $3\\times 3$ neutrino mixing matrix almost unitary in realistic seesaw models?","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Shun Zhou, Zhi-zhong Xing","submitted_at":"2005-12-22T09:18:15Z","abstract_excerpt":"A simple extension of the standard model is to introduce $n$ heavy right-handed Majorana neutrinos and preserve its $\\rm SU(2)^{}_L \\times U(1)^{}_Y$ gauge symmetry. Diagonalizing the $(3+n) \\times (3+n)$ neutrino mass matrix, we obtain an exact analytical expression for the effective mass matrix of $\\nu^{}_e$, $\\nu^{}_\\mu$ and $\\nu^{}_\\tau$. It turns out that the $3\\times 3$ neutrino mixing matrix $V$, which appears in the leptonic charged-current weak interactions, must not be exactly unitary. The unitarity violation of $V$ is negligibly tiny, however, if the canonical seesaw mechanism works"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/0512290","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/hep-ph/0512290/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}