Chiral Four-Dimensional N=1 Supersymmetric Type IIA Orientifolds from Intersecting D6-Branes

TL;DR

This paper constructs four-dimensional N=1 supersymmetric type IIA orientifold models with intersecting D6-branes, achieving realistic gauge groups and chiral matter, including a Standard Model-like example with three families and additional particles.

Contribution

It introduces a new class of supersymmetric type IIA orientifold models with intersecting D6-branes that realize Standard Model-like gauge groups and chiral matter, including the first such example with three families.

Findings

Constructed a supersymmetric model with SU(3)_C x SU(2)_L x U(1)_Y gauge group and three families.

Included right-handed neutrinos and exotic multiplets in the model.

Related constructions to known orientifolds via small instanton transitions.

Abstract

We construct N=1 supersymmetric four-dimensional orientifolds of type IIA on T^6/(Z_2 x Z_2) with D6-branes intersecting at angles. The use of D6-branes not fully aligned with the O6-planes in the model allows for a construction of many supersymmetric models with chiral matter, including those with the Standard Model and grand unified gauge groups. We perform a search for realistic gauge sectors, and construct the first example of a supersymmetric type II orientifold with SU(3)_C x SU(2)_L x U(1)_Y gauge group and three quark-lepton families. In addition to the supersymmetric Standard Model content, the model contains right-handed neutrinos, a (chiral but anomaly-free) set of exotic multiplets, and diverse vector-like multiplets. The general class of these constructions are related to familiar type II orientifolds by small instanton transitions, which in some cases change the number of generations, as discussed in specific models. These constructions are supersymmetric only for special choices of untwisted moduli. We briefly discuss the supersymmetry breaking effects away from that point. The M-theory lift of this general class of supersymmetric orientifold models should correspond to purely geometrical backgrounds admitting a singular G_2 holonomy metric and leading to four-dimensional M-theory vacua with chiral fermions.