On ortho-positronium and gauge
arXiv:0805.4337
Abstract
Binding energy of the state (ortho-positronium) in QED is calculated using the one-photon exchange Bethe-Salpeter equation in the Feynman and Coulomb gauges for different coupling constants . Calculations show there is a remarkable difference in values of the binding energy for different coupling constants in these two gauges.
18 pages