Parameters
QCD vacuum:
Multiple topological sectors |n⟩. True vacuum: |θ⟩ = Σ e^(inθ)|n⟩
Instanton:
Tunneling between |n⟩ and |n+1⟩. Self-dual solution: F=±*F in Euclidean time. Action S = 8π²/g².
Strong CP:
L ⊃ (θ+ArgDetM)·(g²/32π²)GG̃ violates CP if θ≠0. Neutron EDM: |θ|<10⁻¹⁰.
Energy:
E(θ) = −K cos(θ) where K ∝ instanton density
Multiple topological sectors |n⟩. True vacuum: |θ⟩ = Σ e^(inθ)|n⟩
Instanton:
Tunneling between |n⟩ and |n+1⟩. Self-dual solution: F=±*F in Euclidean time. Action S = 8π²/g².
Strong CP:
L ⊃ (θ+ArgDetM)·(g²/32π²)GG̃ violates CP if θ≠0. Neutron EDM: |θ|<10⁻¹⁰.
Energy:
E(θ) = −K cos(θ) where K ∝ instanton density