Constraining ${\alpha }_s(M_Z)$ from the Hidden Sector

Abstract

By including the effects of superstring thresholds, we reconsider minimal string unification together with the requirement of producing a supersymmetry-breaking gluino condensate in the hidden sector. This gives, for examples of phenomenologically-viable $Z_8^{\prime }$ and other related orbifolds, the constraint that $0.1215\le {\alpha }_s(M_Z)\le 0.1270$. In such models, a hidden photino can be a source of cosmological dark matter detectable by gravitational microlensing.

12 pages (23k), in ReVTeX plus 3 postscript figures (27k), Submitted to Physical Review Letters