D=4, N=1 orientifolds with vector structure

TL;DR

This paper constructs specific N=1 supersymmetric type IIB orientifold models with vector structure, demonstrating tadpole cancellation through an alternative projection, expanding the landscape of consistent orientifold compactifications.

Contribution

It introduces the concept of vector structure in Z_N orientifolds with even N, enabling tadpole cancellation in models previously thought inconsistent.

Findings

Vector structure causes a sign flip in twisted Klein bottle contributions.

All tadpoles can be canceled with D9- and D5-branes in these models.

Models with vector structure are consistent and anomaly-free.

Abstract

We construct compact type IIB orientifolds with discrete groups Z_4, Z_6, Z_6', Z_8, Z_12 and Z_12'. These models are N=1 supersymmetric in D=4 and have vector structure. The possibility of having vector structure in Z_N orientifolds with even N arises due to an alternative Omega-projection in the twisted sectors. Some of the models without vector structure are known to be inconsistent because of uncancelled tadpoles. We show that vector structure leads to a sign flip in the twisted Klein bottle contribution. As a consequence, all the tadpoles can be cancelled by introducing D9-branes and D5-branes.