{"paper":{"title":"Lessons from $f(R,R_c^2,R_m^2, L_m)$ gravity: Smooth Gauss-Bonnet limit, energy-momentum conservation and nonminimal coupling","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.CO","hep-th"],"primary_cat":"gr-qc","authors_text":"David Wenjie Tian, Ivan Booth","submitted_at":"2014-04-30T18:25:01Z","abstract_excerpt":"This paper studies a generic fourth-order theory of gravity with Lagrangian density $f(R,R_c^2,R_m^2, \\mathscr{L}_m)$. By considering explicit $R^2$ dependence and imposing the \"coherence condition\" $f_{R^2}\\!=\\!f_{R_m^2}\\!=\\! -f_{R_c^2}/4$, the field equations of $f(R,R^2,R_c^2,R_m^2, \\mathscr{L}_m)$ gravity can be smoothly reduced to that of $f(R,\\mathcal{G},\\mathscr{L}_m)$ generalized Gauss-Bonnet gravity. We use Noether's conservation law to study the $f(\\mathcal{R}_1,\\mathcal{R}_2\\ldots,\\mathcal{R}_n,\\mathscr{L}_m)$ model with nonminimal coupling between $\\mathscr{L}_m$ and Riemannian inv"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1404.7823","kind":"arxiv","version":3},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"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"}