Is dark matter a thermal-relic weakly interacting massive particle?
In plain words
A popular idea is that dark matter is a heavy particle that was in equilibrium with ordinary matter in the hot early universe and froze out at the right abundance. Underground detectors look for it hitting atomic nuclei.
Precise statement
Does a particle of mass $1\,\mathrm{GeV}\text{ to }100\,\mathrm{TeV}$, produced by thermal freeze-out with annihilation cross section $\langle \sigma v\rangle \sim 3e-26\,\mathrm{cm}^{3}/\mathrm{s}$, make up $\Omega_c$? Answer yes (a detection of nuclear recoils, annihilation products or collider production consistent with the thermal cross section) or no for named benchmarks: exclusion of Higgs-portal and Z-portal thermal relics by direct detection, and of the pure wino ($\sim 2.9\,\mathrm{TeV}$) and pure Higgsino ($\sim 1.1\,\mathrm{TeV}$) thermal relics by gamma-ray line and continuum searches from the Galactic Center. Thermal relics with loop-suppressed nuclear couplings (pure Higgsino, $\sigma_{\mathrm{SI}} \sim 1e-49\text{ to }1e-48\,\mathrm{cm}^{2}$) lie at or below the xenon neutrino background floor, so direct detection alone cannot close the question.
What would settle it
Liquid-xenon or argon detectors reaching the neutrino background floor over $10\,\mathrm{GeV}$ to $10\,\mathrm{TeV}$, combined with gamma-ray line and continuum searches sensitive to wino and Higgsino annihilation at the thermal cross section.
Status in the literature
Unverified note
LZ (2025, 4.2 tonne-years) found no excess and excluded spin-independent WIMP-nucleon cross sections above $2.2e-48\,\mathrm{cm}^{2}$ at 40 GeV (90 percent confidence).
Related problems
- Special case of What is dark matter made of?