Theoretical Foundations of Oscillating Brane Dark Matter - Part 2
4. Comparative Analysis
4.1 Model Comparison Table
Criterion | Oscillating Brane | ΛCDM | MOND |
---|---|---|---|
DM Nature | Geometric effect from extra dimensions | Unknown particles (WIMPs, axions) | No DM, modified gravity |
Theoretical Basis | String theory/M-theory (RS extension) | Particle physics extensions | Empirical modification |
Free Parameters | 3 (τ₀, f_osc, L) | 2+ (Ω_c, σ_v, m_χ) | 1 (a₀) + relativistic ext. |
CMB Fit Quality | ΔC_ℓ/C_ℓ < 10⁻³ | χ²/dof ≈ 1.00 | Poor without 2eV neutrinos |
Galaxy Rotations | v⁴ ∝ M_b automatically | Requires NFW/Einasto profiles | v⁴ ∝ M_b by design |
Tully-Fisher σ | ~0.05 dex predicted | ~0.3 dex (with scatter) | ~0.05 dex (built-in) |
Cluster M/L ratio | 300-400 (factor 5-6 boost) | 200-500 (varies) | Fails without DM |
Bullet Separation | 150 kpc naturally | Explained (collisionless) | Unexplained |
Cusp-Core | Cores ~10 kpc | Cusps (ρ ∝ r⁻¹) | Cores (by construction) |
Missing Satellites | Factor 2-3 reduction | Too many by 5-10× | Better match |
Direct Detection | σ < 10⁻⁴⁸ cm² forever | σ > 10⁻⁴⁷ cm² expected | No prediction |
S₈ Tension | Resolved (-5.2%) | 3σ tension | Not addressed |
H₀ Tension | Potential resolution | 5σ tension | Not addressed |
GW Prediction | f₀ = 1.6×10⁻¹⁷ Hz | None specific | None |
Falsifiability | Multiple clear tests | Particle discovery | Limited tests |
4.2 Advantages Over Competitors
vs ΛCDM:
- Explains DM-baryon coupling naturally
- No need for undiscovered particles
- Potentially resolves small-scale issues
- Provides unified framework (DM + DE from branes)
vs MOND:
- Works at all scales (galaxies to cosmology)
- No need for complicated relativistic extensions
- Explains cluster dynamics and lensing
- Compatible with CMB observations
5. Testable Predictions and Falsifiability
5.1 Numerical Predictions Table
Observable | Prediction | Uncertainty | Detection Method | Timeline |
---|---|---|---|---|
Fundamental Parameters | ||||
Brane tension τ₀ | 7.0 × 10¹⁹ J/m² | ±15% | Indirect via H₀(z) | Current |
Oscillation period T | 2.0 Gyr | ±0.3 Gyr | GW spectrum | 2030+ |
Extra dimension L | 0.2 μm | Factor of 2 | KK modes | 2035+ |
KK mass m_KK | 1 eV | ±0.5 eV | Cosmological bounds | Current |
Cosmological Effects | ||||
S₈ suppression | -5.2% | ±0.5% | Weak lensing | Current |
w(z) amplitude A_w | 0.003 | ±0.001 | BAO + SNe | 2025+ |
H₀ anisotropy | 0.01% | ±0.005% | Precision cosmology | 2030+ |
Gravitational Waves | ||||
Fundamental f₀ | 1.6 × 10⁻¹⁷ Hz | ±10% | PTA arrays | 2035+ |
Strain h_c | 2 × 10⁻¹⁸ | Factor of 3 | SKA-PTA | 2035+ |
Spectral index n_t | 2/3 | ±0.1 | NANOGrav+ | 2025+ |
Galactic Scale | ||||
MOND a₀ | 1.1 × 10⁻¹⁰ m/s² | ±5% | Galaxy dynamics | Current |
Halo core radius | ~10 kpc | ±3 kpc | Stellar kinematics | 2025+ |
Subhalo reduction | Factor 2-3 | ±50% | Stream gaps | 2028+ |
Particle Physics | ||||
Branon mass | ~1 eV | Order of magnitude | Non-detection | Current |
DM cross-section | < 10⁻⁴⁸ cm² | Lower limit | Direct detection | Current |
LHC production | < 10⁻⁵⁰ fb | Upper limit | Collider searches | Current |
5.2 Unique Signatures
-
No Direct Detection: The model predicts null results in all particle DM searches (XENON, LUX, etc.)
- Gravitational Wave Spectrum:
- Doublet at $(f_0, 2f_0)$ with strain $h_c \sim 2 \times 10^{-18}$
- Phase transition background at nHz frequencies
- Detectable by SKA-PTA + LISA (2035+)
- Modified Halo Structure:
- Fewer subhalos than ΛCDM (factor ~2-3)
- Smoother density profiles (no cusps)
- Testable via stellar streams and microlensing
- Spatial Gravity Variations:
- $\delta g/g \sim 10^{-8}$ at supercluster boundaries
- Directional H₀ variations ~0.01%
- Future precision astrometry tests
- Baryon-DM Coupling:
- Tighter correlation than ΛCDM expects
- Deviations in ultra-diffuse galaxies
- Predictable from baryon distribution alone
5.3 Falsification Criteria
The model would be falsified by:
- Direct detection of DM particles with $\sigma > 10^{-48}$ cm²
- Absence of GW doublet with sensitivity $< 10^{-19}$
- Discovery of DM-dominated structures without baryons
-
Variations in fundamental constants beyond $ \dot{G}/G > 10^{-13}$ yr⁻¹
5.4 Quantum Loop Corrections and Stability
Quantum Corrections to Brane Tension
The quantum stability of the oscillating brane requires careful analysis. One-loop corrections to the effective brane tension are:
\[\delta\tau_{1-loop} = \frac{\Lambda_{UV}^4}{(4\pi)^2} \ln\left(\frac{\Lambda_{UV}}{m_\phi}\right)\]where $\Lambda_{UV}$ is the UV cutoff and $m_\phi \sim 1$ eV is the radion mass.
Key result: For $\Lambda_{UV} < M_5$ (the 5D Planck mass), corrections remain small: \(\frac{\delta\tau_{1-loop}}{\tau_0} < 10^{-3}\)
This ensures quantum corrections don’t destabilize the classical oscillation.
Branon Properties
The quantum excitations of the brane (branons) have:
- Mass: $m_{branon} \approx 1$ eV (set by extra dimension size $L \sim 0.2 \mu$m)
- Coupling: Only gravitational, suppressed by $M_P^{-2}$
- Lifetime: $\tau_{branon} > 10^{30}$ years (cosmologically stable)
- Production rate: Negligible in colliders due to gravitational coupling
Prediction: No branon production at LHC energies ($\sigma < 10^{-50}$ fb)
Decay Rate Analysis
The oscillation mode decay rate via graviton emission:
\[\Gamma_{decay} = \frac{m_\phi^5}{M_5^3} \approx 10^{-70} \text{ Hz}\]Since $\Gamma_{decay} \ll H_0 \approx 10^{-18}$ Hz, the oscillations persist through cosmic time.