The Neutral Chaoiton: A Falsifiable Dark Matter Candidate from the Ouroboros Lagrangian Constraints from Existing Public Data and Projections for Near-Term Tests

The nature of dark matter remains unknown after four decades of increasingly sensitive searches. Weakly Interacting Massive Particles (WIMPs) are excluded over most of their natural parameter space; axions remain undetected; the conventional smooth-halo picture is demonstrably wrong at the scale of our own solar neighborhood. We present the neutral chaoiton — a stable, time-periodic, localized soliton of the Ouroboros Lagrangian — as a concrete, falsifiable dark matter candidate requiring no new free parameters. The Ouroboros Lagrangian (Werbos 2026, Paper I) is a superrenormalizable classical field theory dynamically equivalent to its own canonical quantization, with only three free parameters fixed by the electron. The neutral chaoiton has mass m_χ = 0.460 MeV and J-field mediator mass m_J = 0.618 MeV — derived from the same calibration that fits the electron g-factor, muon mass, and tau mass with no additional input. This version (v7) incorporates the definitive β(r) profile from the canonical BVP integration (Griesi 2026) to compute the J-field–nucleon coupling from first principles. The zero-momentum mixing integral yields α_eff = 8.56 × 10⁻⁴ and a chaoiton-proton cross-section σ_p = 4.25 × 10⁻²⁹ cm² — a factor of 42.5 above current LZ CRBDM limits. This tension motivates the NEGF refinement underway (Ghosh, UVA) and a systematic scan of parameter space. The self-interaction cross-section σ/m ≈ 5 × 10⁷ cm²/g remains too large for chaoitons to constitute all dark matter, strongly supporting the two-component picture (chaoiton particles + J-field waves). The six-peak annual modulation from Gaia Dark Shards provides a falsifiable signature for a dedicated J-field sensor.