Standard-Like Model Building on Type II Orientifolds
  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. 
Ching-Ming Chen, Tianjun Li, Dimitri V. Nanopoulos