Non-perturbative K3 Orientifolds with NS-NS B-flux

TL;DR

This paper explores non-perturbative six-dimensional N=1 orientifolds of Type IIB string theory on K3 surfaces with NS-NS B-flux, revealing new states and dualities with F-theory compactifications.

Contribution

It provides the first explicit construction of non-perturbative K3 orientifolds with NS-NS B-flux, extending Nikulin's classification via Voisin-Borcea orbifolds.

Findings

Identification of non-perturbative states in twisted open string sectors

Construction of dual F-theory models on Voisin-Borcea orbifolds

Evidence supporting extension of Nikulin's classification

Abstract

We consider non-perturbative six dimensional N=1 space-time supersymmetric orientifolds of Type IIB on K3 with non-trivial NS-NS B-flux. All of these models are non-perturbative in both orientifold and heterotic pictures. Thus, some states in such compactifications arise in ``twisted'' open string sectors which lack world-sheet description in terms of D-branes. We also discuss their dual F-theory compactifications on certain Voisin-Borcea orbifolds. In particular, the explicit construction of non-perturbative K3 orientifolds with NS-NS B-flux gives additional evidence for the conjectured extension of Nikulin's classification in the context of Voisin-Borcea orbifolds.