Low-Energy Signatures of Semi-perturbative Unification

We consider the low-energy signatures of, and high-energy motivations for, scenarios of semi-perturbative gauge coupling unification. Such scenarios can leave striking imprints on the low-energy sparticle spectrum, including novel gaugino mass ratios (including M2/M1 ≈ 1), substantial compression of the intra-generational squark-to-slepton mass ratios, and an overall lifting of scalar masses relative to the gauginos. We also demonstrate that the unification scale can be raised to MX ≈ 4 × 1017 GeV while still in the perturbative regime – close to the 1-loop heterotic string scale. We employ a 3-loop calculation of the running of the gauge couplings as a test of the perturbativity of the high-scale theory. Research supported by Dept. of Energy contract #DE-FG02-90ER40542, and by the W.M. Keck and Monell Foundations. Email addresses: [email protected], [email protected]