Recursion and growth estimates in renormalizable quantum field theory
  In this paper we show that there is a Lipatov bound for the radius of convergence for superficially divergent one-particle irreducible Green functions in a renormalizable quantum field theory if there is such a bound for the superficially convergent ones. The radius of convergence turns out to be ${\rm min}\{\rho,1/b_1\}$, where $\rho$ is the bound on the convergent ones, the instanton radius, and $b_1$ the first coefficient of the $\beta$-function. 
Dirk Kreimer and Karen Yeats