Cosmological Constraints on the Scale of Supersymmetry Breaking

Abstract

We consider the cosmological and astrophysical constraints on the decay of massive $E_8\times E_8^{\prime }$ superstring axions associated with the hidden sector. We find that decay lifetimes greater than 1 s are ruled out by limits from nucleosynthesis, by limits on the distortion of the cosmic microwave and gamma ray backgrounds and by closure arguments. We conclude that $\Lambda >1.2\times 10^{13}\text{gev}$, where $\Lambda$ is the scale of gaugino condensation in the hidden sector. This implies that the scale of supersymmetry breaking is greater than $10^{10}\text{gev}$. Significantly, our result agrees with the value of $5\times 10^{13}\text{gev}$ for $\text{L}$ obtained independently by setting supersymmetric scalar masses equal to $m_W$.

Comments: 14 pages, Constraints on axion decays from limits on photodissociation of light elements revised. No change in final results. Three appendices from companion paper hep-ph/9407323 added. Plain TEX file