The method of flow equations is applied to QED on the light front. Requiring that the particle number conserving terms in the Hamiltonian are considered to be diagonal and the other terms off-diagonal an effective Hamiltonian is obtained which reduces the positronium problem to a two-particle problem, since the particle number violating contributions are eliminated. No infrared divergences appear. The ultraviolet renormalization can be performed simultaneously.

• Received 30 October 1997

DOI:https://doi.org/10.1103/PhysRevD.58.025012