Photino mass and selectron production in unpolarized and polarized ee annihilation

Selectron production in unpolarized e⁺e⁻ collisions is reconsidered for supersymmetric theories with massive photinos. Near threshold the cross section is enhanced by a strong s-wave component enabling, in principle, also the determination of the photino mass. Polarized e⁺e⁻ annihilations into selectron and photino pairs would provide not only an independent and direct measurement of the photino mass but also a clean experimental separation of the two selectrons accompanying the left- and right-handed electron.