The instanton–anti-instanton pair-induced asymptotics of perturbation theory expansion for QCD correlators is considered. It is argued that though the true asymptotics is dominated by the renormalon, the instanton-induced contribution may dominate in the intermediate asymptotics n=5–15. The obtained asymptotic formulas are valid for ${\mathit{N}}_{\mathit{f}}$≤${\mathit{N}}_{\mathit{c}}$. For ${\mathit{N}}_{\mathit{f}}$=${\mathit{N}}_{\mathit{c}}$ the finite nonperturbative expression for the instanton–anti-instanton contribution was also found. At ${\mathit{q}}^2$<0 for ${\mathit{N}}_{\mathit{f}}$=${\mathit{N}}_{\mathit{c}}$ the imaginary part of the correlators is ${\mathrm{\alpha }}_{\mathit{s}}$ times smaller than the real one, but the present accuracy of instanton calculations allows one to fix it unambiguously. The series of corrections to the instanton-induced asymptotics of the order of ∼[ln(n)/n${]}^{\mathit{k}}$ is found.

• Received 1 November 1994

DOI:https://doi.org/10.1103/PhysRevD.51.6587