{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d6fab354c06d7cf2a7f3dbab2be54be70c46cfeb5b1ddee916e12e6ec1be24ed","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"bcf0f869456cc2c86468a713287d6185f5a46082bd01f6952f6e6eec173cbad3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.sub-gev-detection.daily-modulation-anisotropy","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"In a crystal that responds differently along different directions, the signal from dark matter should rise and fall once a day as Earth rotates, while most backgrounds should not. This could distinguish a real signal from the unexplained excess of small events.","posed_since":"","precise":"For sub-GeV dark matter scattering via phonons or electrons in anisotropic crystals (e.g., Al2O3, hexagonal BN, graphene-like or Dirac materials), the rate $R(t)$ modulates with sidereal period because the dark matter wind direction rotates relative to the crystal axes; predicted fractional amplitudes reach tens of percent in some materials. The question is whether a modulation of this size can be measured at sub-eV thresholds with exposure below about $1\\,\\mathrm{kg}\\,\\mathrm{yr}$, given present low-energy excess rates, and whether the excess itself shows any sidereal modulation.","problem_ref":null,"references":"","settled_by":"A sidereal-period analysis of a low-threshold anisotropic-crystal data set with known orientation, giving an amplitude limit or detection at the predicted level.","status_note":"A 2026 preprint (arXiv 2606.04091) estimated halo-model uncertainties of 1-100 percent in single-phonon rates across the mass range, which enter the modulation prediction.","title":"Can daily modulation in anisotropic crystals identify light dark matter?","topic_ref":"e60bc33f70ea44a1215dcfbe7831dd7817b64c21ad3c95ac918a82ec04971901"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"45ca3224045fe4a750c1a11a5bfc843358f7b0115700613cf7f290e3e9ad1baa","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"868f76b3f67442ebdb38a283847a4b7b3b3061d5ba692a08fa0180ed0f4ba4d8","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"8-sPNNDtFFBZx6UDmN4idBki6oKFJQKyZqUfpVoSNQLXSy0yGOk5ka5ASvAM8OFmY0mVaKBZjvPmbR7x907nBA"},"schema":"pubphys.envelope/1"},"record_hash":"45ca3224045fe4a750c1a11a5bfc843358f7b0115700613cf7f290e3e9ad1baa","leaf_index":1586}