A K-theory anomaly free supersymmetric flipped SU ( 5 ) model from intersecting branes

We construct an N = 1 supersymmetric three-family flipped SU ( 5 ) model from type IIA orientifolds on T 6 / ( Z 2 × Z 2 ) with D6-branes intersecting at general angles. The model is constrained by the requirement that Ramond–Ramond tadpoles cancel, the supersymmetry conditions, and that the gauge boson coupled to the U ( 1 ) X factor does not get a string-scale mass via a generalised Green–Schwarz mechanism. The model is further constrained by requiring cancellation of K-theory charges. The spectrum contains a complete grand unified and electroweak Higgs sector, however the latter in a non-minimal number of copies. In addition, it contains extra matter both in bi-fundamental and vector-like representations as well as two copies of matter in the symmetric representation of SU ( 5 ) .