Chiral D-brane Models with Frozen Open String Moduli

Most intersecting D-brane vacua in the literature contain additional masslessadjoint fields in their low energy spectrum. The existence of these additionalfields make it difficult to obtain negative beta functions and, eventually,asymptotic freedom. We address this important issue for N=1 intersectingD-brane models, rephrasing the problems in terms of (open string) modulistabilization. In particular, we consider a Z2 x Z2 orientifold constructionwhere D6-branes wrap rigid 3-cycles and such extra adjoint fields do not arise.We derive the model building rules and consistency conditions for intersectingbranes in this background, and provide N=1 chiral vacua free of adjoint fields.More precisely, we construct a Pati-Salam-like model whose SU(4) gauge group isasymptotically free. We also comment on the application of these results forobtaining gaugino condensation in chiral D-brane models. Finally, we embed ourconstructions in the framework of flux compactification, and construct newclasses of N=1 and N=0 chiral flux vacua.Comment: 55 pages, 4 figures. Bibtex forma