{"paper":{"title":"An Observational Determination of the Proton to Electron Mass Ratio in the Early Universe","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"Carlos Martins, Daniel Eisenstein, Jill Bechtold, John H. Black, J. Xavier Prochaska, Robert C. Kennicutt, Rodger I. Thompson, Xiaohui Fan, Yancey L. Shirley","submitted_at":"2009-07-24T22:56:17Z","abstract_excerpt":"In an effort to resolve the discrepancy between two measurements of the fundamental constant mu, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the molecular hydrogen absorption lines in archival VLT/UVES spectra of the damped Lyman alpha systems in the QSOs Q0347-383 and Q0405-443 yields a combined measurement of a (Delta mu)/mu value of (-7 +/- 8) x 10^{-6}, consistent with no change in the value of mu over a time span of 11.5 gigayears. Here we define (Delta mu) as (mu_z - mu_0) where mu_z is the valu"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0907.4392","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":""},"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"}