{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"44277948978c9188c81e308e0728dbc1a5a8bc6bf3168449744368d0e3b0c8d9","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"cd754013c451e1bcea1ceaab95c429e0f0e3c1ee4d3f6a38623873b26170c9f1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"cosmo.cmb-anomalies.cosmic-birefringence","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"A hypothetical very light field filling space could rotate the polarization of light on its journey from the early universe. A small rotation angle has been reported, but it is hard to separate from instrument calibration errors.","posed_since":"2020","precise":"Measure the isotropic polarization rotation angle $\\beta$, which converts $E$-modes into $B$-modes and produces nonzero EB correlations; analyses of Planck and WMAP using Galactic foreground EB as calibration reported $\\beta \\sim 0.34 \\pm 0.09\\ \\mathrm{degrees}$ (about $3.6\\sigma$, 2022). Answer whether $\\beta$ is nonzero with detector polarization angles calibrated independently to below $0.05\\ \\mathrm{degrees}$.","problem_ref":null,"references":"","settled_by":"Measurement of $\\beta$ with ground-based or space CMB polarization experiments using artificial calibration sources or lunar and planetary references.","status_note":"ACT DR6 (2025, arXiv:2509.13654) measured $\\beta = 0.215 \\pm 0.074\\,\\mathrm{degrees}\\ (2.9\\,\\sigma)$, consistent with Planck and WMAP but still limited by polarization-angle calibration.","title":"Is CMB polarization rotated by a parity-violating field?","topic_ref":"803af421679c0e0814e18e65c97707fa962470e07595871c548569ba9a62aa1d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"0a448543904268849471e5eaf2acfe87113c0a358651cff3153a8e7d7366742c","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"26e951ae88ab3266defe02da2f7982e14049ee178c21f767c20fa5606ce4a157","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"6XF0Ap9V_eokBcS_SOMe6H8sMbU-yRkXDsa2_-Hp4aKcXE31KbhBcxCtZ02a1CuF6b89ATvPoGeoaPueVf6MBQ"},"schema":"pubphys.envelope/1"},"record_hash":"0a448543904268849471e5eaf2acfe87113c0a358651cff3153a8e7d7366742c","leaf_index":1224}