T-branes as branes within branes

TL;DR

This paper investigates T-branes in type IIB string theory, revealing their unconventional properties, such as non-standard gauge groups and matter localization, through tachyon condensation analysis.

Contribution

It provides a new perspective by diagonalizing tachyons in T-branes, simplifying the understanding of gauge groups and matter spectra, and uncovers matter localization at unexpected loci.

Findings

Tachyon can be diagonalized even when the Higgs cannot.

Matter localizes at unexpected points in certain models.

Lower-dimensional branes bound to 7-branes when tachyon is not diagonalizable.

Abstract

Bound states of 7-branes known as 'T-branes' have properties that defy usual geometric intuition. For instance, the gauge group of n coincident branes may not be U(n). More surprisingly, matter may show up at unexpected loci, such as points. By analyzing T-branes of perturbative type IIB string theory in the tachyon condensation picture we gain the following insights: In a large class of models, the tachyon can be diagonalized even though the worldvolume Higgs cannot. In those cases, we see the structure of these bound states more manifestly, thereby drastically simplifying analysis of gauge groups and spectra. Whenever the tachyon is not diagonalizable, matter localizes at unexpected loci, and we find that there is a lower-dimensional brane bound to the 7-brane.