2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/197550Orbifold compactification of heterotic E8 x E8 string theory is a source for promising grand unified model building. It can accommodate the successful aspects of grand unification while avoiding problems like doublet-triplet splitting in the Higgs sector. Many of the phenomenological properties of the 4-dimensional effective theory find an explanation through the geometry of compact space and the location of matter and Higgs fields. These geometrical properties can be used as a guideline for realistic model building.33 pages, 11 figuresHigh Energy Physics - TheoryHigh Energy Physics - Phenomenologytext