D-brane probes on G2 Orbifolds

TL;DR

This paper investigates D1-branes probing G2 orbifolds in type IIB string theory, analyzing the low energy sigma-model and proposing a novel twisted mass mechanism to smooth out singularities in the moduli space.

Contribution

It introduces a new twisted mass coupling for D-branes on G2 orbifolds, modifying the vacuum structure without D-terms, and generalizes the moment map concept.

Findings

The low energy theory is a (1,1) supersymmetric sigma-model.

A twisted mass term removes the orbifold singularity.

The mechanism generalizes the moment map for moduli stabilization.

Abstract

We consider type IIB string theory on a seven dimensional orbifold with holonomy in G2. The motivation is to use D1-branes as probes of the geometry. The low energy theory on the D1-brane is a sigma-model with two real supercharges (N = (1,1) in two dimensional language). We study in detail the closed and open string sectors and propose a coupling of the twisted fields to the brane that modifies the vacuum moduli space so that the singularity at the origin is removed. Instead of coming from D-terms, which are not present here, the modification comes from a ``twisted'' mass term for the seven scalar multiplets on the brane. The proposed mechanism involves a generalization of the moment map.