{"paper":{"title":"Observable windows for the QCD axion through $N_\\text{eff}$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.CO","hep-th"],"primary_cat":"hep-ph","authors_text":"Alessio Notari, Ricardo Z. Ferreira","submitted_at":"2018-01-18T15:15:34Z","abstract_excerpt":"We show that when the QCD axion is directly coupled to quarks with $c_q/f \\, \\partial_\\mu a \\, \\bar{q} \\gamma^\\mu \\gamma^5 q$, such as in DFSZ models, the dominant production mechanism in the early universe at temperatures $1 \\, {\\rm GeV}\\lesssim T \\lesssim 100 \\,{\\rm GeV}$ is obtained via $q \\bar{q} \\leftrightarrow g a$ and $q g \\leftrightarrow q a$, where $g$ are gluons. Different heavy quarks $q_i$ can produce a thermal axion background that decouples at a temperature $T_i$: (1) top quark at $T_t \\lesssim 100 \\, {\\rm GeV}$ for $f/c_t \\lesssim 3\\times 10^8 {\\rm GeV}$; (2) bottom quark at $T_"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1801.06090","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":""},"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"}