Can daily modulation in anisotropic crystals identify light dark matter? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title
Can daily modulation in anisotropic crystals identify light dark matter?
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.
Precise · changed · core
Revision 1: 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.
Revision 2: For sub-GeV dark matter scattering via phonons or electrons in anisotropic crystals (e.g., $\mathrm{Al_2O_3}$, 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.
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.
Kind
well-posed
Answer type
yes-no
References
(empty)
Literature status
open
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.
Posed since
(empty)

Decisions