Decoupling Limits in M-Theory

TL;DR

This paper explores decoupling limits in M-theory involving D-branes, revealing how matter theories emerge at different energy scales and conditions, with specific results on metastable states and decoupling behavior.

Contribution

It provides a detailed analysis of decoupling limits for D-branes in M-theory, especially for n>4, and describes the low and high energy behavior of the resulting matter theories.

Findings

Decoupled matter theories are described by the large N limit of (n+1)-dimensional super Yang-Mills.

At high energies, the matter theory corresponds to a free type II string theory in curved spacetime.

Metastable D6-D0 bound states have energy proportional to M^{1/3}m^{2/3} and decouple under certain conditions.

Abstract

Limits of a system of N Dn-branes in which the bulk and string degrees of freedom decouple to leave a `matter' theory are investigated and, for n>4, either give a free theory or require taking $N \to \infty$. The decoupled matter theory is described at low energies by the $N \to \infty$ limit of n+1 dimensional \sym, and at high energies by a free type II string theory in a curved space-time. Metastable bound states of D6-branes with mass $M$ and D0-branes with mass $m$ are shown to have an energy proportional to $M^{1/3}m^{2/3}$ and decouple, whereas in matrix theory they only decouple in the large N limit.