Open Descendants of Z_2\times Z_2 Freely-Acting Orbifolds

TL;DR

This paper explores Z_2×Z_2 orientifolds with shifts, revealing new type-I models with partial supersymmetry breaking, rich geometries, and dual M-theory descriptions, expanding understanding of string compactifications.

Contribution

It introduces novel type-I models with partial supersymmetry breaking and complex geometries, including deformations and dualities, in Z_2×Z_2 orbifold frameworks.

Findings

Models with N=2→N=1, N=4→N=1, N=4→N=2 supersymmetry breaking.

Rich geometrical structures with gauge groups of reduced rank.

Dual M-theory descriptions of certain models.

Abstract

We discuss Z_2 \times Z_2 orientifolds where the orbifold twists are accompanied by shifts on momentum or winding lattice states. The models contain variable numbers of D5 branes, whose massless (and, at times, even massive) modes have variable numbers of supersymmetries. We display new type-I models with partial supersymmetry breaking N=2 \to N=1, N=4 \to N=1 and N=4 \to N=2. The geometry of these models is rather rich: the shift operations create brane multiplets related by orbifold transformations that support gauge groups of reduced rank. Some of the models are deformations of six-dimensional supersymmetric type-I models, while others have dual M-theory descriptions.