Dark-Matter Hopfion Detection: Protocols for the Soliton Dust

Title: Dark-Matter Hopfion Detection: Protocols for the $H=0$ Soliton Dust

Author: A. Novickis (alex.novickis@gmail.com)

The Hopf soliton programme identifies dark matter with the $H=0$ sector of the programme's field $\hat n: \mathcal M \to S^2$ — a pressureless dust of field-topology defects with mass $\sim 0.89$ MeV (Paper LXVII). Paper CXXV §4.4 notes that $H=0$ hopfions have zero magnetic moment but a non-zero polarisability $\alpha_E \sim 10^{-43}\,{\rm m}^3/{\rm T}^2$, too small for terrestrial $B$-field detection ($\sim 10^{-21}\,{\rm A}\,{\rm m}^2$ induced moment at magnetar fields). But the programme makes several distinct predictions beyond the magnetic polarisability, and this paper lays out the full experimental landscape. We propose five detection strategies: (i) keV-line electron recoil at 0.89 MeV threshold (tabletop); (ii) sub-MeV polarised scattering (accelerator); (iii) stellar cooling at T = 0.15 keV freeze-out temperature (astrophysical); (iv) nuclear resonance in heavy isotopes (tabletop + accelerator); (v) collective-mode excitation in solid-state analogues (condensed matter). Protocols (i) and (v) are within reach of current experiments; (ii) and (iv) require dedicated facilities; (iii) is astrophysical observation. We identify the critical prediction: a 0.89 MeV line in direct-detection experiments that existing WIMP searches (XENONnT, LZ, SuperCDMS) may already be sensitive to at the sub-GeV extension of their analyses.

Keywords: dark matter, direct detection, Hopf soliton, H=0 sector, sub-MeV dark matter, stellar cooling, electron recoil, 0.89 MeV, XENONnT, LZ

Keywords: [physics, dark matter, detection, hopfion, soliton, phenomenology]

Series: Paper CXXVII in the Hopf Soliton Programme