I wonder about to which type of particles gauginos couple in general. I admit my knowledge in supersymmetry is very limited. Let's take an example: The photino. If it behaved similar to the photon, it would for instance couple to electrons and their superpartners. In that case one should notice its effect in electron-electron scattering. However, I haven't heard up to now of any deviation of the standard QED. May be this simply means that the photino does not exist or it is simply too heavy, but anyway I am not sure if my assumption is correct at all. It would be nice if somebody could tell something more reasonable.
In this respect I had asked a similar question Does the gravitino contribute to the gravitational interaction? some time ago and the answer was that it does not contribute as it only couples to the supercurrent (and in particular below the supersymmetry breaking scale it would not couple at all (more or less)). Of course I wondered what that means finally realizing that the supercurrent cannot be measured experimentally as for instance the electric charge, it is just a generator in the superalgebra. The point is that I still don't know to what the gravitino couples. However, this time (with a more global question) I really would appreciate a more obvious answer.