GUT predictions for quark and lepton mass ratios

Group theoretical factors from GUT symmetry breaking can lead to predictions for the ratios of quark and lepton masses at the unification scale. Due to supersymmetric (SUSY) threshold corrections the viability of such predictions can depend strongly on the SUSY parameters. We derive possible new predictions for the GUT scale ratios m_\mu/m_s, y_\tau/y_b and y_t/y_b and compare them with the experimentally allowed ranges for three common SUSY breaking scenarios.Comment: Based on a talk given at SUSY 09; 5 pages, 1 figure, 2 table