Compare · The Dark Universe

WIMPs vs Superfluid Dark Matter

Dark Matter Candidates· within family

	WIMPs Frontier	Superfluid Dark Matter Frontier
Proposed	1977 / 1996	2015
Key figures	Benjamin Lee, Steven Weinberg, Gerard Jungman, Gianfranco Bertone	Lasha Berezhiani, Justin Khoury
In one sentence	Hypothetical particles with masses around the weak scale that interact with ordinary matter via the weak nuclear force and gravity but not light. Their thermal abundance from the early universe naturally matches the observed dark matter density. Direct-detection experiments have been searching for decades and have not seen them.	Lasha Berezhiani and Justin Khoury proposed in 2015 a hybrid dark matter framework: a particle that condenses into a superfluid phase in the central regions of galaxies, producing MOND-like phenomenology on galactic scales via phonon excitations, while remaining ordinary cold dark matter on cosmological scales. Berezhiani and Khoury's 2015 and 2016 papers (Phys. Rev. D 92, 103510 and Phys. Lett. B 753, 639) attempt to bridge particle-DM ontology with MOND-style modified-gravity phenomenology in a single framework.
Predictions	Nuclear recoils with characteristic energy spectrum in xenon or argon detectors at rates set by WIMP-nucleon cross-section, WIMP mass, and local halo density Gamma rays, antimatter, and neutrinos from WIMP-WIMP annihilation in the Galactic center, dwarf spheroidals, and the Sun Missing transverse momentum in LHC events with one or more visible particles (mono-jet, mono-photon, mono-Z) A leftover abundance from the early universe that naturally matches today's dark matter density, the 'WIMP miracle', set by thermal freeze-out (Ωh² ≈ 0.12 for an annihilation rate ⟨σv⟩ ≈ 3×10^-26 cm³/s)	Galactic rotation curves are explained by phonon excitations in the superfluid phase of dark matter; the framework reproduces the MOND empirical relations on galactic scales Galaxy cluster dynamics are governed by standard CDM (the superfluid phase is destroyed at cluster densities), reproducing the empirical successes of dark matter on large scales Cosmological observables (CMB, large-scale structure) are essentially CDM, since the superfluid phase exists only in dense galaxy interiors Specific predictions for the transition radius between superfluid and normal CDM phases in each galaxy, depending on the central density and the dark-matter particle properties
Where it breaks	LHC has produced no evidence of weak-scale supersymmetric WIMPs (neutralinos); natural SUSY models with TeV-scale masses now require fine-tuning Direct-detection limits exclude the simplest weak-cross-section WIMPs for masses where the WIMP miracle was strongest The WIMP miracle is less compelling post-LHC: many of the natural models that gave the coincidence are now constrained or ruled out Critics argue WIMPs are becoming unfalsifiable: every null result is met with a more elaborate model variant	Galaxy cluster constraints (specifically, the Bullet Cluster and related merging-cluster observations) place upper bounds on the dark-matter particle's self-interaction cross-section; the superfluid framework's parameter space is constrained by these observations The framework requires fine-tuning the dark-matter particle's mass and self-interaction parameters to specific ranges that enable superfluid condensation in galaxies but not in clusters; the deep physical motivation for these values is not provided Citation counts for the framework remain below what some researchers consider significant; its current impact is more modest than the bridge-framework ambition suggests Alternative hybrid frameworks (Verlinde Entropic Gravity, modified-inertia variants of MOND) cover similar territory; the choice among bridge frameworks is not currently observationally constrained
Key unresolved problem	The neutrino fog problem: detectors are now so sensitive they pick up a steady drizzle of natural neutrinos, and it is unclear whether a real WIMP signal could ever be told apart from this unavoidable background.	The fine-tuning problem: the particle's mass and interactions must sit in a very narrow range so the dark matter turns into a frictionless superfluid inside galaxies but not in clusters, and there is no deeper reason those exact values should hold.
Reader vote	No votes yet	No votes yet

WIMPs

1977 / 1996 · Frontier

Superfluid Dark Matter

2015 · Frontier

Proposed

1977 / 1996

2015

Key figures

Benjamin Lee, Steven Weinberg, Gerard Jungman, Gianfranco Bertone

Lasha Berezhiani, Justin Khoury

In one sentence

Hypothetical particles with masses around the weak scale that interact with ordinary matter via the weak nuclear force and gravity but not light. Their thermal abundance from the early universe naturally matches the observed dark matter density. Direct-detection experiments have been searching for decades and have not seen them.

Lasha Berezhiani and Justin Khoury proposed in 2015 a hybrid dark matter framework: a particle that condenses into a superfluid phase in the central regions of galaxies, producing MOND-like phenomenology on galactic scales via phonon excitations, while remaining ordinary cold dark matter on cosmological scales. Berezhiani and Khoury's 2015 and 2016 papers (Phys. Rev. D 92, 103510 and Phys. Lett. B 753, 639) attempt to bridge particle-DM ontology with MOND-style modified-gravity phenomenology in a single framework.

Predictions

Nuclear recoils with characteristic energy spectrum in xenon or argon detectors at rates set by WIMP-nucleon cross-section, WIMP mass, and local halo density
Gamma rays, antimatter, and neutrinos from WIMP-WIMP annihilation in the Galactic center, dwarf spheroidals, and the Sun
Missing transverse momentum in LHC events with one or more visible particles (mono-jet, mono-photon, mono-Z)
A leftover abundance from the early universe that naturally matches today's dark matter density, the 'WIMP miracle', set by thermal freeze-out (Ωh² ≈ 0.12 for an annihilation rate ⟨σv⟩ ≈ 3×10^-26 cm³/s)

Galactic rotation curves are explained by phonon excitations in the superfluid phase of dark matter; the framework reproduces the MOND empirical relations on galactic scales
Galaxy cluster dynamics are governed by standard CDM (the superfluid phase is destroyed at cluster densities), reproducing the empirical successes of dark matter on large scales
Cosmological observables (CMB, large-scale structure) are essentially CDM, since the superfluid phase exists only in dense galaxy interiors
Specific predictions for the transition radius between superfluid and normal CDM phases in each galaxy, depending on the central density and the dark-matter particle properties

Where it breaks

LHC has produced no evidence of weak-scale supersymmetric WIMPs (neutralinos); natural SUSY models with TeV-scale masses now require fine-tuning
Direct-detection limits exclude the simplest weak-cross-section WIMPs for masses where the WIMP miracle was strongest
The WIMP miracle is less compelling post-LHC: many of the natural models that gave the coincidence are now constrained or ruled out
Critics argue WIMPs are becoming unfalsifiable: every null result is met with a more elaborate model variant

Galaxy cluster constraints (specifically, the Bullet Cluster and related merging-cluster observations) place upper bounds on the dark-matter particle's self-interaction cross-section; the superfluid framework's parameter space is constrained by these observations
The framework requires fine-tuning the dark-matter particle's mass and self-interaction parameters to specific ranges that enable superfluid condensation in galaxies but not in clusters; the deep physical motivation for these values is not provided
Citation counts for the framework remain below what some researchers consider significant; its current impact is more modest than the bridge-framework ambition suggests
Alternative hybrid frameworks (Verlinde Entropic Gravity, modified-inertia variants of MOND) cover similar territory; the choice among bridge frameworks is not currently observationally constrained

Key unresolved problem

The neutrino fog problem: detectors are now so sensitive they pick up a steady drizzle of natural neutrinos, and it is unclear whether a real WIMP signal could ever be told apart from this unavoidable background.

The fine-tuning problem: the particle's mass and interactions must sit in a very narrow range so the dark matter turns into a frictionless superfluid inside galaxies but not in clusters, and there is no deeper reason those exact values should hold.

Reader vote

No votes yet