Sparticle and Higgs masses within minimal string unification

We consider the sparticle and higgs spectroscopy in a class of superstring inspired models in which the string threshold corrections ensure the consistency of the string unification scale with the low energy data. The lightest neutralino is almost a pure bino and it is predicted to be the lightest sparticle (LSP). Requiring that $\Omega_{LSP}\leq 0.9$, we find an upper bound on its mass which, in the case of dilaton supersymmetry breaking, turns out to be 160 GeV. The LEP 1.5 experimental lower bound on the chargino mass, $m_{\chi^{\pm}} > 65$ GeV, implies that the lower bound on the LSP mass is $m_{LSP} > 32 (45)$ GeV, corresponding to $\mu < (>)0$. We also determine the lower and upper bounds on the higgs and other sparticle masses. For instance, the lightest higgs lies between 65 and 115 GeV, while the mass of the lightest charged sparticle satisfies 47 GeV $ < m_{\tilde{e}_R} < 325$ GeV. With only the top Yukawa coupling of order unity we find that $ 1.5 \leq \tan \beta \leq 3.5$.