Standard-Like Model Building on Type II Orientifolds

TL;DR

This paper tackles the problem of deriving Standard-like physics from Type II orientifolds by building explicit three-family models in Type IIA on T^6/(Z_2×Z_2) with intersecting D6-branes and exploring Type IIB flux compactifications on the same orientifold. It constructs a novel three-family trinification model and several Pati-Salam–like variants in the IIA setting, showing how the Green-Schwarz mechanism, brane splittings, and Higgsing can reproduce the SM gauge group, though Yukawa structures often restrict masses to a subset of families due to anomalous U(1) symmetries. In Type IIB, it demonstrates that trinification cannot be realized with supergravity fluxes because of large RR charges, but a new flux PS-like model with magnetized D9-branes is obtained, balancing D3-charge with additional U(1)s and yielding TeV-scale symmetry breaking with limited fermion-mass generation. Overall, the work clarifies the trade-offs between RR tadpole constraints, SUSY-breaking, and Yukawa couplings in concrete Type II constructions and provides concrete wrapping numbers and spectra for further phenomenological exploration.

Abstract

We construct new Standard-like models on Type II orientifolds. In Type IIA theory on $\mathbf{T^6/(\Z_2\times \Z_2)}$ orientifold with intersecting D6-branes, we first construct a three-family trinification model where the $U(3)_C\times U(3)_L\times U(3)_R$ gauge symmetry can be broken down to the $SU(3)_C\times SU(2)_L\times U(1)_{Y_L}\times U(1)_{I_{3R}}\times U(1)_{Y_R}$ gauge symmetry by the Green-Schwarz mechanism and D6-brane splittings, and further down to the SM gauge symmetry at the TeV scale by Higgs mechanism. We also construct a Pati-Salam model where we may explain three-family SM fermion masses and mixings. Furthermore, we construct for the first time a Pati-Salam like model with $U(4)_C \times U(2)_L \times U(1)' \times U(1)''$ gauge symmetry where the $U(1)_{I_{3R}}$ comes from a linear combination of U(1) gauge symmetries. In Type IIB theory on $\mathbf{T^6/(\Z_2\times \Z_2)}$ orientifold with flux compactifications, we construct a new flux model with $U(4)_C \times U(2)_L \times U(2)_R$ gauge symmetry where the magnetized D9-branes with large negative D3-brane charges are introduced in the hidden sector. However, we can not construct the trinification model with supergravity fluxes because the three SU(3) groups already contribute very large RR charges. The phenomenological consequences of these models are briefly discussed as well.