Renormalon's Contribution to Effective Couplings

When an asymptotically non-free theory possesses a mass parameter, the ultraviolet (UV) renormalon gives rise to non-perturbative contributions to dimension-four operators and dimensionless couplings, thus has a similar effect as the instanton. We illustrate this phenomenon in O(N) symmetric massive $\lambda\phi^4$ model in the $1/N$ expansion. This effect of UV renormalon is briefly compared with non-perturbative corrections in the magnetic picture of the Seiberg-Witten theory.