Particle models from orientifolds at Gepner-orbifold points

TL;DR

The paper develops a framework to produce four-dimensional chiral gauge theories from Type IIB orientifolds on Gepner-orbifold points by phase moddings that embed a $f Z_N$ action into Chan-Paton factors. It combines diagonal Gepner invariants with torus orbifolds and derives modular-invariant projected characters, an open-string index for chirality, and straightforward tadpole-cancellation conditions, enabling unitary gauge groups with chiral matter in both supersymmetric and tachyon-free non-supersymmetric settings. The authors illustrate the method with concrete examples, obtaining chiral spectra and three generation scenarios (e.g., ${f 3^5_D/Z_5}$ and $({f 1^3 imes T^4})/Z_3$) and exploring Standard-like constructions via brane/antibrane setups. This approach yields rank-reduced yet phenomenologically interesting configurations within solvable conformal field theory frameworks, while highlighting avenues for moduli stabilization and broader Gepner–torus combinations.

Abstract

We consider configurations of stacks of orientifold planes and D-branes wrapped on a non trivial internal space of the structure {(Gepner model)^{c=3n} x T^{2(3-n)}}/Z_N, for n=1,2,3. By performing simple moddings by discrete symmetries of Gepner models at orienti fold points, consistent with a Z_N orbifold action, we show that projection on D-brane configurations can be achieved, generically leading to chiral gauge theories. Either supersymmetric or non-supersymmetric (tachyon free) models can be obtained. We illustrate the procedure through some explicit examples.