GUT effects in the soft supersymmetry breaking terms

In minimal supergravity theories the soft supersymmetry breaking (SSB) parameters are universal (flavor blind) near the Planck scale. Nevertheless, one often assumes universality at the grand-unification scale $M_{G} \approx 10^{16}$ GeV instead, and corrections to the SSB parameters arising from their evolution between the Planck and GUT scales are neglected. We study these corrections and show that large splittings between the scalar mass parameters can be induced at $M_{G}$. These effects are model dependent and lead to significant uncertainties in the low-energy predictions of supersymmetric models, in their correlations and in the allowed parameter space.