Kähler moduli stabilization in semirealistic magnetized orbifold models

We study Kähler moduli stabilizations in semirealistic magnetized D-brane models based on $Z_2\times Z_2^{\prime }$ toroidal orbifolds. In type IIB compactifications, 3-form fluxes can stabilize the dilaton and complex structure moduli fields, but there remain some massless closed string moduli fields, Kähler moduli. The magnetic fluxes generate Fayet-Iliopoulos terms, which can fix ratios of Kähler moduli. On top of that, we consider D-brane instanton effects to stabilize them in concrete D-brane models and investigate the brane configurations to confirm that the moduli fields can be stabilized successfully. In this paper, we treat two types of D-brane models. One is based on D9-brane systems respecting the Pati-Salam model. The other is realized in a D7-brane system breaking the Pati-Salam gauge group. We find suitable configurations where the D-brane instantons can stabilize the moduli fields within both types of D-brane models, explaining an origin of a small constant term of the superpotential, which is a key ingredient for successful moduli stabilizations.

Figure 1

A set of three squares expresses a fundamental region of $T^2\times T^2\times T^2$. The left and right sides correspond to each other in T-duality along three vertical axes.

Figure 2

A set of three squares expresses a fundamental region of $T^2\times T^2\times T^2$. The left and right sides correspond to each other in T-duality along three vertical axes.