Variations of the hidden sector in a realistic intersecting brane model

Abstract

Recently, we discussed the first example of a phenomenologically realistic intersecting D6-brane model. In this model, the gauge symmetry in the hidden sector is USp(2)1 × USp(2)2 × USp(2)3 × USp(2)4. However, we find that the USp(2)1 × USp(2)2 gauge symmetry can be replaced by a U(2)12 gauge symmetry, and/or the USp(2)3 × USp(2)4 gauge symmetry can be replaced by a U(2)34 gauge symmetry since the USp(2)2 stacks of D6-branes contribute to the same Ramond–Ramond tadpoles as those of the U(2) stacks. Thus, there are three non-equivalent variations of the hidden sector, and the corresponding gauge symmetries are U(2)12 × USp(2)3 × USp(2)4, U(2)34 × USp(2)1 × USp(2)2 and U(2)12 × U(2)34, respectively. Moreover, we study the hidden sector gauge symmetry breaking, discuss how to decouple the additional exotic particles and briefly comment on the phenomenological consequences.