Axion Quark Nuggets: Dark Matter Candidates

• Axion Quark Nuggets (AQNs) are macroscopic dark matter candidates composed of dense quark or antiquark matter in a color-superconducting phase stabilized by an axion domain wall.
• AQN formation occurs during the QCD transition, producing characteristic mass ranges and unique annihilation signatures that can emit electromagnetic, acoustic, and axionic signals.
• Interactions between AQNs and ambient baryons yield distinct astrophysical and terrestrial phenomena, prompting diverse detection strategies from solar studies to seismic and paleo-detector approaches.

Axion Quark Nuggets (AQNs) are a class of macroscopic dark-matter candidates composed of dense quark matter or antiquark matter in a color-superconducting phase and stabilized by an axion domain wall. In the AQN framework, dark matter and the visible baryonic sector originate from the same QCD-era dynamics, so the near coincidence $\Omega_{\rm DM}\sim \Omega_{\rm visible}$ is treated as a consequence of common QCD-scale physics rather than of unrelated sectors. A defining feature is that the dark sector contains both matter nuggets and antimatter nuggets; the latter are phenomenologically central because annihilation with ambient baryons can generate electromagnetic, acoustic, and axionic signatures across cosmology, astrophysics, and terrestrial environments (Zhitnitsky, 2021).

1. Cosmological framework and baryon-charge separation

The AQN scenario replaces conventional baryogenesis by baryon-charge separation. The total baryon number of the Universe is taken to remain zero, while visible baryons, matter nuggets, and antimatter nuggets partition that charge asymmetrically. Representative bookkeeping relations used in the literature include

$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$

the ratio

$$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$

and, in one cluster-oriented formulation, the partition $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$ (Lazanu et al., 2024, Zhitnitsky, 2021, Sommer et al., 2024). For the observed $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$, the review literature quotes $c\approx 3/2$, so the antibaryon charge hidden in antinuggets exceeds the baryon charge hidden in nuggets (Zhitnitsky, 2021).

Within this picture, the visible matter excess does not arise because the Universe generated a net baryon number, but because more antibaryon number was sequestered into antimatter nuggets than baryon number into matter nuggets. Free visible antibaryons then annihilated away, while visible baryons survived. The baryon-to-photon ratio is correspondingly tied to the AQN formation temperature rather than to a separate late-time baryogenesis sector; the review literature quotes

$$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$

as characteristic numbers in this framework (Zhitnitsky, 2021).

A recurring claim across the AQN literature is therefore that the relation $\Omega_{\rm DM}\sim \Omega_{\rm visible}$ is not an after-the-fact fit but a structural property of QCD-scale formation. This motivates the model independently of any individual phenomenological application, including solar, atmospheric, cluster, or terrestrial search proposals (Zhitnitsky, 2020, Liang et al., 11 Feb 2026).

2. Formation, composition, and characteristic scales

AQNs are assumed to form near the QCD transition from closed $N_{\rm DW}=1$ axion-domain-wall bubbles that accrete quarks and antiquarks while collapsing. In the review treatment, numerical simulations suggest that about $87\%$ of the total wall area belongs to one large percolating cluster, while the remaining $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$0 appears as relatively small closed bubbles that seed nugget formation. Collapse is arrested by quark Fermi pressure, and the final object reaches a dense color-superconducting state with $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$1 and pairing gap $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$2 at $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$3 and $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$4–$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$5 (Zhitnitsky, 2021).

The characteristic conserved quantity is the baryon number $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$6. The standard scalings are

$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$7

Because of this $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$8 suppression, the cross-section-to-mass ratio can be as small as

$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$9

well below the usual collisionless-dark-matter criterion $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$0 (Zhitnitsky, 2021, Majidi et al., 5 Dec 2025). The model is thus “dark” not because of weak couplings in the WIMP sense, but because the nuggets are very massive and correspondingly rare.

The literature uses a broad allowed baryon-number interval. Representative ranges are $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$1 or $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$2, with direct nondetection bounds often quoted as $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$3 or $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$4 (Zhitnitsky, 2020, Zhitnitsky, 2021, Liang et al., 11 Feb 2026). Recent cosmological and astrophysical analyses commonly work in the practical mass interval $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$5, while some CMB and diffuse-emission studies emphasize benchmarks $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$6 or $$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$7–$$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$8 (Majidi et al., 5 Dec 2025, Liang et al., 11 Feb 2026, Sekatchev et al., 21 Apr 2025).

For a representative mass-radius relation at nuclear density, one recent CMB study writes

$$\Omega_{\rm DM}\approx \left(\frac{1+c}{1-c}\right)\Omega_{\rm B},\qquad c\equiv \frac{|B_{\bar N}|}{|B_N|}\sim {\cal O}(1),$$9

so $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$0 corresponds to $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$1 (Majidi et al., 5 Dec 2025). Atmospheric and terrestrial phenomenology often uses a comparable benchmark: for $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$2, $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$3 and mass is of order $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$4 g (Zhitnitsky, 2020).

3. Interaction physics with baryons and radiation fields

AQN phenomenology is governed by interactions between ambient baryons and the nugget surface or electrosphere. A general local rate model used in cosmological emission calculations is

$$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$5

where $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$6 is the effective capture cross section, $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$7 is baryon density, and $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$8 is the relative AQN-baryon speed (Majidi et al., 2024). A proton-antiproton annihilation event is taken to release approximately $$B_{\rm \bar{AQN}}:B_{\rm AQN}:B_{\rm visible}\simeq 3:2:1$$9, with a phenomenological split between a thermalized channel, which heats the electrosphere, and a prompt non-thermal electromagnetic channel. The thermal electrosphere emission is modeled by a bremsstrahlung-like surface emissivity

$\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$0

and the corresponding spectral emissivity

$\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$1

with $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$2 given piecewise in the electrosphere calculations (Majidi et al., 2024, Sommer et al., 2024).

A crucial environmental effect is electrosphere ionization. As loosely bound positrons are removed, an antimatter nugget acquires a net negative charge, which can increase proton capture in ionized media through Coulomb attraction. In large-scale-structure calculations this is encoded via $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$3 and $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$4 when the gas is ionized and the Coulomb capture radius exceeds the geometric radius (Majidi et al., 2024). In the early Universe, a related mechanism gives an effective ion-capture enhancement around recombination,

$\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$5

with $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$6 over $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$7, so Debye screening is subdominant in the redshift range relevant for the CMB distortion calculation (Majidi et al., 5 Dec 2025).

In dense terrestrial media, the microphysics becomes more uncertain. The paleo-detector study models anti-AQN stopping by analogy with “nuclearite-like” energy loss and with antiproton annihilation on nuclei. It uses

$\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$8

with $\Omega_{\rm DM}\approx 5\,\Omega_{\rm B}$9 in the lithosphere, implying a crossover near $c\approx 3/2$0 for rock densities $c\approx 3/2$1–$c\approx 3/2$2. The same work quotes annihilation-based stopping powers

$c\approx 3/2$3

for atmosphere and

$c\approx 3/2$4

for rock, together with the caveat that an extra suppression factor $c\approx 3/2$5 or smaller may arise if positron removal from the electrosphere reduces annihilation efficiency (Lazanu et al., 2024).

Because the annihilation of nuclei on antiquark matter in a color-superconducting phase is not experimentally known, several studies explicitly substitute antiproton-annihilation phenomenology. The paleo-detector analysis uses $c\approx 3/2$6 together with mean pion multiplicity $c\approx 3/2$7, average pion energy $c\approx 3/2$8, and average emitted proton multiplicity $c\approx 3/2$9 as input for FLUKA simulations (Lazanu et al., 2024). This substitution is one of the central unresolved modeling assumptions in the entire AQN phenomenology.

4. Astrophysical and cosmological phenomenology

Solar applications are among the most developed. One simulation-based study argues that AQNs can account for the quiet-Sun coronal EUV and soft-X-ray power $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$0, with most of the energy deposited near the transition region at altitude $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$1. In that framework, impacting anti-AQNs lose more than $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$2 of their mass before reaching the photosphere, and the corresponding event energies map naturally onto the nanoflare interval $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$3 through $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$4 (Raza et al., 2018). A related flare-oriented study further proposes that the same incoming anti-AQNs, moving through the solar atmosphere at $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$5, have Mach number $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$6 and can generate shocks with $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$7 and $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$8, thereby acting as triggers of magnetic reconnection in active regions while the flare energy itself remains magnetic (Zhitnitsky, 2018).

Atmospheric AQN phenomenology has been used to interpret the short-duration, thunderstorm-correlated Telescope Array burst events. In that proposal, an antimatter AQN moving through the atmosphere is heated to $$\eta \equiv \frac{n_B-n_{\bar B}}{n_\gamma}\simeq \frac{n_B}{n_\gamma}\sim 10^{-10}, \qquad T_{\rm form}\simeq 41~{\rm MeV}$$9–$\Omega_{\rm DM}\sim \Omega_{\rm visible}$0, develops a weakly bound positron cloud extending to

$\Omega_{\rm DM}\sim \Omega_{\rm visible}$1

and, in a thunderstorm electric field of order $\Omega_{\rm DM}\sim \Omega_{\rm visible}$2, can liberate and accelerate positrons to $\Omega_{\rm DM}\sim \Omega_{\rm visible}$3. The same paper estimates a detector-scale positron yield $\Omega_{\rm DM}\sim \Omega_{\rm visible}$4, burst path length $\Omega_{\rm DM}\sim \Omega_{\rm visible}$5 for $\Omega_{\rm DM}\sim \Omega_{\rm visible}$6, and predicts synchronized radio emission in the $\Omega_{\rm DM}\sim \Omega_{\rm visible}$7–$\Omega_{\rm DM}\sim \Omega_{\rm visible}$8 MHz band (Zhitnitsky, 2020).

Several works extend AQN emission to large-scale environments. In cosmological large-scale-structure forecasts, the AQN-baryon interaction generates both a monopole signal and anisotropy fluctuations from radio to a few keV, with the amplitude depending strongly on average nugget mass and on the ionization state of the baryonic environment. The most optimistic scenarios were found to lie near the sensitivity limit of existing instruments such as FIRAS and the South Pole Telescope, while the best prospects were identified as ultra-deep IR/optical surveys, CMB spectral distortions, and high-resolution low-frequency observations in the $\Omega_{\rm DM}\sim \Omega_{\rm visible}$9–$N_{\rm DW}=1$0 GHz range (Majidi et al., 2024). A companion cluster analysis, using 161 simulated galaxy clusters and 11 cross-identified observed systems, predicts that thermal AQN emission can exceed standard intracluster backgrounds in a low-frequency window up to $N_{\rm DW}=1$1 in favorable cases; Fornax and Virgo are identified there as the most promising named cluster targets (Sommer et al., 2024). On Galactic scales, a Milky Way study using FIRE-2 Latte solar-neighborhood analogs finds that the AQN-induced far-UV glow can match the observed diffuse FUV excess for $N_{\rm DW}=1$2–$N_{\rm DW}=1$3, with the observational benchmark quoted as about $N_{\rm DW}=1$4–$N_{\rm DW}=1$5 (Sekatchev et al., 21 Apr 2025).

Early-Universe consequences have also been quantified. A recent CMB study finds that AQN-induced baryon annihilation leaves CMB anisotropies essentially unaffected but can produce spectral distortions of order

$N_{\rm DW}=1$6

with the characteristic prediction $N_{\rm DW}=1$7 arising because the AQN heating history scales approximately as $N_{\rm DW}=1$8, slightly steeper than standard annihilating dark matter (Majidi et al., 5 Dec 2025). An earlier cosmological application addresses the primordial lithium problem by arguing that at $N_{\rm DW}=1$9, negatively charged antinuggets can preferentially capture nuclei with $87\%$0, giving an order-unity depletion of Li and Be while leaving H and He essentially unaffected because the capture enhancement scales exponentially with $87\%$1 (Flambaum et al., 2018).

5. Terrestrial searches and detector concepts

Because AQNs are massive and rare, terrestrial searches often emphasize large passive targets, wide-area coincidence, or multimessenger signatures rather than conventional compact detectors. A general flux normalization used in network and acoustic studies is

$87\%$2

corresponding to roughly one event per day per $87\%$3 area for $87\%$4 (Budker et al., 2020, Liang et al., 2020).

One class of proposals targets acoustic and seismic disturbances. A dedicated infrasound study predicts that atmospheric anti-AQNs should generate infrasonic pulses near $87\%$5–$87\%$6. For a typical $87\%$7 event, the estimated overpressure at $87\%$8 is $87\%$9, whereas a rarer $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$00 event at $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$01 can give $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$02 and $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$03. Underground, the same work estimates much stronger kHz-band disturbances, with benchmark overpressure $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$04 at $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$05 and frequency $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$06, motivating Distributed Acoustic Sensing and seismic-network searches (Budker et al., 2020).

A second class uses synchronized detector networks. For AQN-induced axions, one proposal argues that the optimal geometry is a triangular network of stations separated by $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$07, because this matches the expected local-flash radius and allows trajectory reconstruction from burst timing. For X-rays, the same study finds that the optimal elementary unit is a regular tetrahedron with $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$08 spacing, since X-rays attenuate locally and four detectors are needed for unique three-dimensional reconstruction. In its simulations, the underground-emission constraint yields $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$09 unique trajectory reconstruction for a triangular axion network, while a tetrahedral X-ray unit gives $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$10 uniqueness (Liang et al., 2020). Related work on AQN-origin axions emphasizes broadband detection rather than narrow cavity haloscopes, because these axions are relativistic with $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$11, broad spectral support $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$12, and daily and annual modulation at the $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$13 level (Budker et al., 2019).

A third class exploits geological exposure. A recent paleo-detector proposal suggests that naturally occurring minerals can register anti-AQN annihilation or transit through a localized, approximately spherically symmetric overdose region readable by thermoluminescence (TL) or optically stimulated luminescence (OSL). The suggested minerals are fluorite/calcium fluoride $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$14, quartz/silicon dioxide $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$15, and feldspars. The paper quotes a smallest TL-recorded dose of $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$16 for $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$17 and a lowest detectable dose of $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$18 for sedimentary quartz, and concludes that at $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$19 m from the interaction point, the electron/positron component alone exceeds detectability if more than $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$20 protons annihilate in $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$21 or more than $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$22 annihilations occur in $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$23, provided the minerals remained at low, stable temperatures over geological timescales (Lazanu et al., 2024).

More unconventional proposals continue this logic of repurposing large existing systems. One 2026 study argues that a subset of LHC Unidentified Falling Object beam-loss events may be triggered by anti-AQNs passing underground within $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$24 of the accelerator. For benchmark masses $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$25–$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$26, it estimates an AQN-induced UFO burst rate $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$27, corresponding to roughly $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$28 of all UFOs. In its background model, requiring three correlated UFOs within $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$29 yields $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$30 over the full allowed AQN mass range after about $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$31 hours, effectively using the LHC as a large broadband acoustic detector (Liang et al., 11 Feb 2026).

6. Open issues, variants, and empirical status

Across the literature, AQNs remain a highly structured but model-dependent framework. The recurring uncertainties are the nonperturbative QCD formation dynamics, the size or mass distribution $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$32, the detailed properties of the color-superconducting phase, the electrosphere microphysics, and the annihilation of nuclei on antiquark matter. Phenomenological papers are explicit that many observational estimates are order-of-magnitude or proof-of-principle calculations rather than end-to-end detector forecasts or precision exclusion plots (Zhitnitsky, 2021, Lazanu et al., 2024, Zhitnitsky, 2020).

These uncertainties appear in different forms in different subfields. Solar applications depend on the effective interaction radius $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$33 and on shock-coupling in the transition region; atmospheric burst models depend on poorly controlled thunderstorm electric fields, the annihilation/thermalization parameter $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$34, and the liberated positron fraction $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$35; large-scale-structure forecasts depend sensitively on ionization state and relative-velocity modeling; paleo-detector proposals depend critically on thermal history, spatially differential backgrounds, and the actual topology of a moving, continuously annihilating antinugget rather than a single idealized point source (Raza et al., 2018, Zhitnitsky, 2020, Majidi et al., 2024, Lazanu et al., 2024).

The literature also explores nonstandard AQN variants. One such variant assumes that AQNs become ferromagnetic, with surface magnetic field $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$36. In that case axion electrodynamics induces an electric field

$$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$37

and the corresponding study estimates a critical magnetic field $$B_{\rm tot}=0=B_{\rm nuggets}-B_{\rm antinuggets}+B_{\rm visible},$$38 above which Schwinger pair production becomes large. Its conclusion is that strongly magnetized “electric” AQNs are likely only marginally viable and probably relax to ordinary non-magnetized AQNs if they are to survive as dark matter today (Santillan et al., 2019).

Empirically, the AQN program currently consists of a web of linked interpretations and search concepts rather than a single decisive test. The review literature presents AQNs as a unified alternative to WIMP dark matter that simultaneously addresses dark matter, baryon asymmetry, and axion physics, while the more specialized papers develop concrete signatures in the Sun, atmosphere, large-scale structure, the CMB, rocks, acoustic media, synchronized detector networks, and accelerator infrastructure (Zhitnitsky, 2021). A plausible synthesis is that the framework is most constrained not by one channel alone but by whether the same mass scale, charge state, and interaction prescriptions can remain mutually consistent across these disparate environments.