A check of quantum electrodynamics and of electron-muon equivalence

A study of the timelike reaction e+e-→μ∓μ± and of its comparison with the spacelike dominated reaction e+e−→e±e± allows us to establish the validity of QED in terms of production angular distributions, absolute rates, energy dependence and angular correlations between the pair of final-state leptons, in two very different ranges of invariant four-momentum transfer. No sign of QED break is detected in the electromagnetic interaction of leptons and the muon behaves like a heavy electron, within the accuracy of the present investigation.