Renormalons in QED

Four-dimensional Quantum Electrodynamics is studied in the limit of a large number of leptons (N->infinite) up to terms of order 1/N inclusive. It is proven that closed analytic expressions can be given for the Borel transform of Green's functions. Furthermore, an appropriate renormalization scheme is introduced. In this scheme, up to first order in the 1/N expansion, all the renormalization group functions are polynomials. Since renormalon singularities are explicitly known, the Borel summability of QED is discussed. (orig.)