“…For interaction terms such as Yukawa couplings, exact string theoretic results are only known on the six-torus, e.g. [8,9], and its T 6 /Z 2 × Z 2 orbifold without discrete torsion, and consequently a treatment of Standard Model (SM) vacua in globally consistent supersymmetric D6-brane models on T 6 /Z 6 [10,11,12,13,3,7] or other T 6 /Z 2N [14,15,16] and T 6 /Z 2 × Z 2M backgrounds with discrete torsion [17,18] has not been performed. To go one step further in the understanding of the field theory of intersecting fractional D6-brane SM vacua, we assume here that the formula for Yukawa couplings on the six-torus directly carries over to its orbifolds and extends to the new case with chiral matter at one vanishing angle, i.e.…”