About Superpartners and the Origins of the Supersymmetric Standard Model

We recall the obstacles which seemed, long ago, to prevent supersymmetry from possibly being a fundamental symmetry of Nature. Which bosons and fermions could be related? Is spontaneous supersymmetry breaking possible? Where is the spin-1/2 Goldstone fermion of supersymmetry? Can one define conserved baryon and lepton numbers in such theories, although they systematically involve self-conjugate Majorana fermions? etc.. We then recall how an early attempt to relate the photon with a ``neutrino'' led to the definition of R-invariance, but that this ``neutrino'' had to be reinterpreted as a new particle, the photino. This led us to the Supersymmetric Standard Model, involving the SU(3) x SU(2) x U(1) gauge interactions of chiral quark and lepton superfields, and of two doublet Higgs superfields responsible for the electroweak breaking and the generation of quark and lepton masses. The original continuous R-invariance was then abandoned in favor of its discrete version, R-parity -- reexpressed as (-1)^2S (-1)^(3B+L) -- so that the gravitino and gluinos can acquire masses. We also comment about supersymmetry breaking.