{"paper":{"title":"Bimodular Gravity: Vacuum Evolution with a Frame-Dependent Phantom Crossing","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["astro-ph.CO","hep-th"],"primary_cat":"gr-qc","authors_text":"James Hallam, Jo\\~ao Magueijo","submitted_at":"2025-11-17T16:28:37Z","abstract_excerpt":"Unimodular gravity recasts the cosmological constant as an integration constant, fixed by a constraint on the volume element rather than chosen in the action. We ask what becomes of this constant when matter couples not to the gravitational metric, but to a second metric disformally related to it through a scalar field. Imposing a volume constraint on each metric, we find a theory in which the scalar does not propagate, yet still drives a non-trivial expansion. Written as a single-metric theory, its kinetic term is fixed to a prescribed function of spacetime, and the cosmological constant is r"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2511.13562","kind":"arxiv","version":2},"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/2511.13562/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"}