DP Universality
ρ ~ (λ−λc)^β, β≈0.276
ξ_⊥ ~ |λ−λc|^{-ν_⊥}, ν_⊥≈1.097
ξ_∥ ~ |λ−λc|^{-ν_∥}, ν_∥≈1.734
Running simulation...
Theory
The contact process is the simplest model with an absorbing state (all empty). Above λc, activity survives (active phase). Below λc, activity dies out. This DP transition belongs to the directed percolation universality class — conjectured to be universal for single absorbing states with no extra symmetries (Janssen-Grassberger conjecture).