Ph.D., Massachusetts Institute of Technology, 1963
Theoretical Elementary Astroparticle Physics
Supersymmetry provides a pivotal context for new physics beyond the highly successful but conceptually incomplete Standard Model of Weak, Electromagnetic, and Strong Interactions. However, supersymmetry, which enforces a pairing between elementary particles of different intrinsic angular momenta, cannot be an exact symmetry of nature, for such a pairing is not observed at present. In the context of modern elementary particle theory, such a symmetry is “softly broken”, and becomes manifest at extremely short distances or at very high energies or temperatures. In particular, it is thought that supersymmetry was a good symmetry during the very earliest stages of the universe, and only as the universe cooled did its broken phase become dominant. The broken phase is widely thought to originate in the formation of a ‘gaugino condensate’ (like a liquid out of the vapor phase), with the dynamics governing the condensation being controlled by the physics of a hidden sector, perhaps originating in string theory. Professor Goldberg has examined several aspects of this phase transition, and has shown how the underlying theory must be constrained in order that this mechanism succeed.
Also in the realm of supersymmetry, Professor Goldberg in collaboration with a graduate student (M. GÃ³mez), has examined the embedding of supersymmetry in an important candidate for a Grand Unified Theory (called SO(10)). In particular, they have studied a very interesting aspect of this embedding — the possibility of observing certain processes in the laboratory which are otherwise predicted to be non-observable. A prime example is the decay of the mu particle into an electron and a gamma ray, and the class of theories studied by GÃ³mez and Goldberg yields a decay probability which should render the process observable during the coming analysis of the new data.
An additional puzzle in modern elementary particle theory is an apparently small, but distinct gap between the energy scale at which the weak, electromagnetic and strong forces become of equal strength (the so-called Grand Unified, or GUT scale) and the scale at which gravity also achieves parity of strength with these forces (the Planck, or string scale). Professor Goldberg has recently proposed a new mechanism which can generate this gap. It rests on a shift of the normal ground state (or vacuum) of the theory induced by the multiplicity of states to which certain fields (‘gauge singlets’), ubiquitous in string theories, are coupled. Professor Goldberg is looking to embed this mechanism in the favored Grand Unified Theory, SO(10).
226 Dana Research Center