Geometry of gauge symmetry breaking in the superstring context

The Higgs mechanism has a very natural global formulation: given a principal fiber bundle (P,M,G), with structural group G, a subbundle with the unbroken subgroup as structural group (with the aid of the Higgs fields themselves) can be constructed. In superstring theory, the fundamental E8 symmetry, as well as the grand unification symmetry, are broken in a very different way. The principal purpose of this work is to construct a global formulation of the superstring gauge vacuum, without Higgs fields