We consider the cosmological constraints on supersymmetric theories with a new, stable particle. Circumstantial evidence points to a neutral gauge/Higgs fermion as the best candidate for this particle, and we derive bounds on the parameters in the lagrangian which govern its mass and couplings. One favored possibility is that the lightest neutral supersymmetric particle is predominantly a photino ∼γ with mass above 1 2 GeV, while another is that the lightest neutral supersymmetric particle is a Higgs fermion with mass above 5 GeV or less than O(100) eV. We also point out that a gravitino mass of 10 to 100 GeV implies that the temperature after completion of an inflationary phase cannot be above 1014 GeV, and probably not above 3 × 1012 GeV. This imposes constraints on mechanisms for generating the baryon number of the universe.
Bibliographical noteFunding Information:
* Work supported by the Department of Energy, contract DE-AC03-76SF00515. t Address as of July 1, 1983: Fermilab, PO Box 500, Batavia, IL 60510. * Address as of Sept. 1, i983: Dept. of Physics, University of Cahfornia, Santa Barbara, CA 93106.