Constraints on SUSY-GUT unification from $b\to s\gamma$ decay
  The top-quark Yukawa infrared fixed-point solution of the renormalization group equations, with minimal supersymmetry and GUT unification, defines a low-energy spectrum of supersymmetric particle masses in terms of a few GUT-scale parameters assuming universal boundary conditions. We give predictions in this model for the inclusive $b\to s\gamma$ branching fraction and investigate the impact of non-universal scalar mass boundary conditions. We find our results do not depend significantly on the value of the GUT-scale trilinear coupling $A^G$. The small $\tan \beta $ region favors predictions for the inclusive $b\to s\gamma$ branching fraction close to that of the Standard Model value. Nevertheless forthcoming experimental results can eliminate some regions of the GUT parameter space. 
V. Barger, M. S. Berger, P. Ohmann, and R. J. N. Phillips