{"paper":{"title":"A constraint on a varying proton--electron mass ratio 1.5 billion years after the Big Bang","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"Australia), J. Bagdonaite (1), J. B. Whitmore (2) ((1) VU University Amsterdam, M. T. Murphy (2), Netherlands (2) Swinburne University of Technology, W. Ubachs (1)","submitted_at":"2015-01-22T15:25:11Z","abstract_excerpt":"A molecular hydrogen absorber at a lookback time of 12.4 billion years, corresponding to 10$\\%$ of the age of the universe today, is analyzed to put a constraint on a varying proton--electron mass ratio, $\\mu$. A high resolution spectrum of the J1443$+$2724 quasar, which was observed with the Very Large Telescope, is used to create an accurate model of 89 Lyman and Werner band transitions whose relative frequencies are sensitive to $\\mu$, yielding a limit on the relative deviation from the current laboratory value of $\\Delta\\mu/\\mu=(-9.5\\pm5.4_{\\textrm{stat}} \\pm 5.3_{\\textrm{sys}})\\times 10^{"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1501.05533","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"}