Gamma/Z interference in e+e- -> mu+ mu-

• Calculate analytically the cross section for $e^{+ e}- \to \mu^{+ \mu}-$ as function of the CMS energy, including both exchange of a photon and a Z boson. Neglect masses of the external fermions. Compare your result with MadGraph.
• The Forward-Backward asymmetry is $A_{FB}(\theta)=\frac{ d\sigma (\theta) - d\sigma(\pi-\theta)}{ d\sigma (\theta) + d\sigma(\pi-\theta)}$. Plot it as a function of the CMS energy.

-- Main.FabioMaltoni - 30 Aug 2007