2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/119057Two-dimensional sigma-models describing superstrings propagating on manifolds of special holonomy are characterized by symmetries related to covariantly constant forms that these manifolds hold, which are generally non-linear and close in a field dependent sense. The thesis explores various aspects of the special holonomy symmetries.PhD thesis, 149 pages; King's College London, 2006High Energy Physics - Theorytext