Power corrections to the heavy electron form factor

Abstract: We study the first power correction to the heavy electron form factor in QED. We show that the first power correction factorizes as a derivative operator. We discuss the result in QED with no light fermions, where the first power correction can be written explicitly in terms of one loop integrals and the anomalous magnetic moment. In the presence of light fermions, the heavy electron form factor admits a representation as a sum over matrix elements, each of which receives corrections from higher orders in perturbation theory. From this analysis we are able to extract the NLP soft photon theorem in the limit of heavy fermion initiated dijet events. This is a first step towards studying the heavy quark form factor in the non-abelian theory.