The running of the effective electromagnetic coupling is for many electroweak observables the dominant correction. It plays an important role for deriving constraints on the Standard Model in the context of electroweak precision measurements. We compute the four-loop QED corrections to the running of the effective electromagnetic coupling and perform a numerical evaluation of the different gauge invariant subsets.
@article{arxiv.1305.0581,
title = {Leptonic contributions to the effective electromagnetic coupling at four-loop order in QED},
author = {Christian Sturm},
journal= {arXiv preprint arXiv:1305.0581},
year = {2013}
}