Comments on D-Brane and $SO(2N)$ Enhanced Symmetry in Type II String

TL;DR

This paper discusses a D-brane configuration that explains the enhancement of $SO(2N)$ gauge symmetry in type II string theory compactified on a $D_n$-type singularity, with evidence from ALE and D-manifold perspectives.

Contribution

It proposes a specific D-brane setup responsible for $SO(2N)$ symmetry enhancement in type II string theory on $D_n$ singularities, addressing perturbative detection issues.

Findings

Proposed D-brane configuration explains symmetry enhancement.

Evidence from $D_n$-type ALE and D-manifold analysis.

Discussion of perturbative visibility of the enhanced symmetry.

Abstract

We propose a configuration of D-branes welded by analogous orbifold operation to be responsible for the enhancement of $SO(2N)$ gauge symmetry in type II string compactified on the $D_n$-type singular limit of K3. Evidences are discussed from the $D_n$-type ALE and D-manifold point of view. A subtlety regarding the ability of seeing the enhanced $SO(2N)$ gauge symmetry perturbatively is briefly addressed.