Associated production of sfermions and gauginos at high-energy e+e- colliders

In the context of the minimal supersymmetric extension of the standard model, we analyze the production at future high-energy e+e- colliders of second and third generation scalar leptons as well as scalar quarks in association with neutralinos and charginos, e+e- → ff̃ χ. In the case of third generation squarks, we also discuss the associated production with gluinos. We show that the cross sections for some of these three-body final state processes could be significant enough to allow for the detection of scalar fermions with masses above the kinematical two-body threshold, s1/2 = 2mf̃. We then discuss, taking as a reference example the case of scalar muons, the production cross sections in various approximations and make a comparison with the full four-body production process, e+e- → ff̄ χχ, in particular around the two-sfermion threshold.