ON SUPERPARTNERS AND THE ORIGINS OF 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-½ 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 introduction 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)×SU(2)×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.