D=4,N=1, Type IIB Orientifolds

TL;DR

This paper explores the construction and constraints of D=4, N=1 type IIB orientifolds on toroidal orbifolds, revealing more restrictive tadpole cancellation conditions and developing models with diverse brane configurations and anomaly cancellation mechanisms.

Contribution

It provides new constructions of D=4, N=1 orientifolds with various brane setups, including models with discrete torsion and analysis of their anomaly cancellation and dualities.

Findings

Tadpole cancellation conditions are more restrictive in four dimensions.

Constructed models with different brane configurations, many chiral.

Identified generalized Green-Schwarz mechanism for anomaly cancellation.

Abstract

We study different aspects of the construction of D=4, N=1 type IIB orientifolds based on toroidal Z_N and Z_M x Z_N, D=4 orbifolds. We find that tadpole cancellation conditions are in general more constraining than in six dimensions and that the standard Gimon-Polchinski orientifold projection leads to the impossibility of tadpole cancellations in a number of Z_N orientifolds with even N including Z_4, Z_8, Z_8' and Z_{12}'. We construct D=4, Z_N and Z_N x Z_M orientifolds with different configurations of 9-branes, 5-branes and 7-branes, most of them chiral. Models including the analogue of discrete torsion are constructed and shown to have features previously conjectured on the basis of F-theory compactified on four-folds. Different properties of the D=4, N=1 models obtained are discussed including their possible heterotic duals and effective low-energy action. These models have in general more than one anomalous U(1) and the anomalies are cancelled by a D=4 generalized Green-Schwarz mechanism involving dilaton and moduli fields.