Regularization-independent studies of nonperturbative field theory

We propose a regularization independent method for studying a renormalizabl e field theory nonperturbatively through its Dyson-Schwinger equations. Usi ng QED(4) as an example, we show how the coupled equations determining the nonperturbative fermion and photon propagators can be written entirely in t erms of renormalized quantities, which renders the equations manifestly fin ite in a regularization-independent manner. As an illustration of the techn ique, we apply it to a study of the fermion propagator in quenched QED(4) w ith the Curtis-Pennington electron-photon vertex. At large momenta the mass function, and hence the anomalous mass dimension gamma (m)(alpha), is calc ulated analytically and we find excellent agreement with previous work. Fin ally, we show that for the CP vertex the perturbation expansion of gamma (m )(alpha) has a finite radius of convergence. (C) 2001 Published by Elsevier Science B.V.