A Matrix Theory Construction of the IIA/IIB Wall

TL;DR

This paper constructs a non-perturbative lightlike domain wall between IIA and IIB string theories in 10D using matrix models within DLCQ, revealing brane transformations at the wall.

Contribution

It provides a novel matrix theory-based construction of the IIA/IIB domain wall, connecting 2D Super Yang-Mills and 3D ABJM theories in a non-perturbative framework.

Findings

BPS IIA D0-branes become non-BPS IIB D0-branes crossing the wall.

String coupling vanishes at the wall, enabling the construction.

Relates matrix models to the IIA/IIB domain wall in 10D string theory.

Abstract

In this note, we give a non-perturbative construction of a lightlike domain wall separating IIA and IIB string theories in 10D in the framework of discrete light-cone quantization (DLCQ). In this setting, generalizations of the BFSS conjecture relate the 10D flat space limit to matrix string theories (MSTs) for IIA and IIB. The former is equivalent to the large-$N$ limit of 2D Super Yang-Mills theory, while the latter is the large-$N$ limit of 3D ABJM theory with $\pm 1$ Chern-Simons levels. Our construction requires the string coupling to vanish at the location of the wall, and we show that BPS IIA $D0$-branes become non-BPS IIB $D0$-branes as they cross it, as anticipated in \cite{Heckman:2025wqd}.