The effective action of D6-branes in N=1 type IIA orientifolds

TL;DR

This paper derives the low-energy effective action for D6-branes in type IIA Calabi-Yau orientifolds, detailing the moduli, gauge couplings, and scalar potential, consistent with mirror symmetry and supergravity principles.

Contribution

It provides a detailed computation of the effective action, including Kahler potential, gauge kinetic functions, and scalar potential, for D6-branes in N=1 type IIA orientifolds, extending previous models.

Findings

Derived Kahler potential and gauge kinetic functions including kinetic mixing.

Expressed the scalar potential in superpotential terms.

Reproduced D-term potential via gauging Peccei-Quinn symmetries.

Abstract

We use a Kaluza-Klein reduction to compute the low-energy effective action for the massless modes of a spacetime-filling D6-brane wrapped on a special Lagrangian 3-cycle of a type IIA Calabi-Yau orientifold. The modifications to the characteristic data of the N=1 bulk orientifold theory in the presence of a D6-brane are analysed by studying the underlying Type IIA supergravity coupled to the brane worldvolume in the democratic formulation and performing a detailed dualisation procedure. The N=1 chiral coordinates are found to be in agreement with expectations from mirror symmetry. We work out the Kahler potential for the chiral superfields as well as the gauge kinetic functions for the bulk and the brane gauge multiplets including the kinetic mixing between the two. The scalar potential resulting from the dualisation procedure can be formally interpreted in terms of a superpotential. Finally, the gauging of the Peccei-Quinn shift symmetries of the complex structure multiplets reproduces the D-term potential enforcing the calibration condition for special Lagrangian 3-cycles.