Calculation of subcritical exponents for corrections to scaling

The "subcritical" exponent Δ₂ₛ for corrections to asymptotic scaling in the renormalization-group theory of critical phenomena, has been calculated for the continuous-spin versions of the classical, $d=3$ Ising, X-Y, and Heisenberg models by numerical integrations of Wilson's approximate recursion formula. The results are Δ₂ₛ(Ising)=-0.640, Δ₂ₛ(X-Y)=-0.644, and Δ₂ₛ(Heisenberg)=-0.647. Comparison is made with results from perturbation expansions in ε=4-d (d being the dimensionality), high-temperature series expansions, and experimental measurements.