The $e^+e^-$ pair production at $\mu^+\mu^-$ collider
  The main source of \epe pair at $\mu^+\mu^-$ collider is incoherent process $\mu^+\mu^-\to \mu^+\mu^-\epe$ with cross section about 10 mb (at muon energy 2 TeV). The corresponding distributions are discussed briefly. These pairs give the dangerous background. The coherent production of \epe pairs here is negligibly small. 
Ilya F. Ginzburg