Magnetized four-dimensional Z2×Z2 orientifolds

Abstract

We study deformations of Z 2 × Z 2 (shift-)orientifolds in four dimensions in the presence of both uniform Abelian internal magnetic fields and quantized NS-NS B ab backgrounds, that are shown to be equivalent to asymmetric shift-orbifold projections. These models are related by T -duality to orientifolds with D-branes intersecting at angles. As in corresponding six-dimensional examples, D9-branes magnetized along two internal directions acquire a charge with respect to the R-R six form, contributing to the tadpole of the orthogonal D5-branes ("brane transmutation"). The resulting models exhibit rank reduction of the gauge group and multiple matter families, due both to the quantized B ab and to the background magnetic fields. Moreover, the lowenergy spectra are chiral and anomaly free if additional D5-branes longitudinal to the magnetized directions are present, and if there are no Ramond-Ramond tadpoles in the corresponding twisted sectors of the undeformed models.

Chiral D-brane Models with Frozen Open String Moduli

“…There is also some recent work on the so-called shifted Z 2 × Z 2 orientifolds [74][75][76][77]. These constructions involve D-branes on top of the orientifold planes and with non-trivial magnetic fluxes on them.…”

“…These constructions involve D-branes on top of the orientifold planes and with non-trivial magnetic fluxes on them. Looking carefully at the models discussed in [76], one realizes that they contain completely rigid branes (named N = 1 supersymmetric branes in the above reference). The geometric construction of these rigid cycles is somewhat analogous to what we will present in this paper.…”

“…with the exception of D6-branes of the form (31). When faced to build semirealistic models, this constraint naturally leads to consider vacua whose low energy spectrum contains a Pati-Salam gauge group and matter content.…”

“…In particular, important issues, such as the pattern of soft SUSY breaking terms [11][12][13][14][15] and the signatures and stability of cosmic strings (see [16][17][18] for some reviews) formed at the end of brane inflation [19,20], depend critically on how the Standard Model (SM) is embedded. In the past few years, the intersecting brane (and, in the T-dual picture, magnetized D-brane) world scenario [21][22][23][24][25][26] has proven to be a promising framework to construct semi-realistic, D = 4, N = 1 chiral string models [27][28][29][30][31][32]. 1 More importantly, it has recently been realized [11,37,38] that by turning on background NSNS and RR fluxes in magnetized D-branes models, SUSY can be softly broken while satisfying the supergravity equation of motion (hence the usual problem of the classical instability in non-supersymmetric models due to non-vanishing NSNS tadpoles is absent).…”

One in a billion: MSSM-like D-brane statistics

“…More concretely, we study supersymmetric intersecting D-brane models on the T 6 Z 2 ×Z 2 orientifold background, which has enjoyed great interest in the past (see e.g. [37][38][39][40][41] among many others). We consider the ensemble of solutions to the tadpole cancellation conditions using 1 Criticism of the landscape idea is expressed in [24,25].…”