München 2019 – scientific programme
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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik
MP 7: Eichtheorien
MP 7.3: Talk
Wednesday, March 20, 2019, 12:00–12:20, HS 23
Equivalence of two different gauges in External Current QED — •Benedikt Wegener1 and Wojciech Dybalski2 — 1Department of Mathematics, University of Rome Tor Vergata, Italy — 2Department of Mathematics, Technical University Munich, Germany
We study the connection between QED in the axial gauge and the Coulomb gauge in the external current approximation. To avoid the severe singularities present in the axial gauge, we use Yngvason-Mund-Schroer type angular smearing. In this formulation, the problem of unitary equivalence of the two gauges can be rigorously posed. We will show that such equivalence holds if the total electric charge of the system is zero. Interestingly, for non-zero electric charge, the equivalence appears to fail due to a different low-energy behaviour of the two gauges. The problem of obtaining the Yngvason-Mund-Schroer potential by canonical quantisation (with constraints) of a certain classical theory will also be discussed.