Is dark matter a thermal-relic weakly interacting massive particle? · revision history
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Superseded · first revision · record
- Title
- Is dark matter a thermal-relic weakly interacting massive particle?
- Plain
- 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
- 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.
- Settled by
- 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.
- Kind
- well-posed
- Answer type
- yes-no
- References
- (empty)
- Literature status
- open
- Status 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).
- Posed since
- 1977