This paper explores the cosmological constraints on supersymmetric theories, focusing on the lightest supersymmetric particle (LSP). The authors consider the possibility that the LSP is a neutral gauge/Higgs fermion, which could have a mass above ½ GeV or less than 100 eV. They derive bounds on the parameters of the Lagrangian that govern the mass and couplings of this particle. The study also examines the implications of a gravitino mass of 10 to 100 GeV, which would impose constraints on the temperature after inflation, limiting it to below 10¹⁴ GeV. This has implications for the generation of the universe's baryon number. The paper discusses various candidates for the LSP, including charged winos, charged higgsinos, sleptons, sneutrinos, gluinos, squarks, and gravitinos. It concludes that these particles are unlikely to be the LSP due to cosmological and experimental constraints. Instead, the LSP is most likely a mixture of neutral gauge and Higgs fermions. The authors analyze the annihilation rates of these particles to determine their cosmological viability, finding that a photino with a mass above ½ GeV is a favored candidate. Alternatively, a Higgsino with a mass above 5 GeV or less than 100 eV could also be the LSP. The study also considers the cosmological implications of a very light Higgsino, which would behave similarly to a neutrino. However, such a particle would require a specific model to avoid conflicts with particle physics experiments. The authors conclude that the LSP is most likely a neutral gauge/Higgs fermion with a mass in the range of ½ to 2 GeV, and that a very light Higgsino is compatible with observations if its mass is below 100 eV. The results are summarized in figures, showing the allowed parameter space for different masses and mixing parameters. The study provides a comprehensive analysis of the cosmological constraints on supersymmetric theories, emphasizing the importance of considering both theoretical and experimental evidence in determining the nature of the LSP.This paper explores the cosmological constraints on supersymmetric theories, focusing on the lightest supersymmetric particle (LSP). The authors consider the possibility that the LSP is a neutral gauge/Higgs fermion, which could have a mass above ½ GeV or less than 100 eV. They derive bounds on the parameters of the Lagrangian that govern the mass and couplings of this particle. The study also examines the implications of a gravitino mass of 10 to 100 GeV, which would impose constraints on the temperature after inflation, limiting it to below 10¹⁴ GeV. This has implications for the generation of the universe's baryon number. The paper discusses various candidates for the LSP, including charged winos, charged higgsinos, sleptons, sneutrinos, gluinos, squarks, and gravitinos. It concludes that these particles are unlikely to be the LSP due to cosmological and experimental constraints. Instead, the LSP is most likely a mixture of neutral gauge and Higgs fermions. The authors analyze the annihilation rates of these particles to determine their cosmological viability, finding that a photino with a mass above ½ GeV is a favored candidate. Alternatively, a Higgsino with a mass above 5 GeV or less than 100 eV could also be the LSP. The study also considers the cosmological implications of a very light Higgsino, which would behave similarly to a neutrino. However, such a particle would require a specific model to avoid conflicts with particle physics experiments. The authors conclude that the LSP is most likely a neutral gauge/Higgs fermion with a mass in the range of ½ to 2 GeV, and that a very light Higgsino is compatible with observations if its mass is below 100 eV. The results are summarized in figures, showing the allowed parameter space for different masses and mixing parameters. The study provides a comprehensive analysis of the cosmological constraints on supersymmetric theories, emphasizing the importance of considering both theoretical and experimental evidence in determining the nature of the LSP.