e+e−→γ+ missing neutrals: Neutrino versus photino production

We have calculated the cross sections for the processes $e^{+}$ $e^{\mathrm{-}}$→γνν¯ and $e^{+}$ $e^{\mathrm{-}}$→γγ̃γ̃. The local-limit approximation for the W-exchange diagram was not used and the integration over the neutrino and photino phase space was done analytically. The use of polarized beams is discussed as a way to improve the signal-to-background ratio of the supersymmetric process.