Massive type IIA string theory cannot be strongly coupled

TL;DR

This paper argues that massive type IIA string theory cannot reach strong coupling in weakly curved regions, supported by explicit solutions in AdS4xCP3 that show the dilaton decreases before entering M-theory regime.

Contribution

It demonstrates that massive type IIA string theory cannot be strongly coupled in weakly curved spacetime, providing explicit solutions and analyzing their behavior at large N.

Findings

Massive type IIA cannot be strongly coupled in weakly curved regions.

Explicit AdS4xCP3 solutions with different supersymmetries analyzed.

Presence of light branes from D2-D0 bound states at large N.

Abstract

Understanding the strong coupling limit of massive type IIA string theory is a longstanding problem. We argue that perhaps this problem does not exist; namely, there may be no strongly coupled solutions of the massive theory. We show explicitly that massive type IIA string theory can never be strongly coupled in a weakly curved region of space-time. We illustrate our general claim with two classes of massive solutions in AdS4xCP3: one, previously known, with N = 1 supersymmetry, and a new one with N = 2 supersymmetry. Both solutions are dual to d = 3 Chern-Simons-matter theories. In both these massive examples, as the rank N of the gauge group is increased, the dilaton initially increases in the same way as in the corresponding massless case; before it can reach the M-theory regime, however, it enters a second regime, in which the dilaton decreases even as N increases. In the N = 2 case, we find supersymmetry-preserving gauge-invariant monopole operators whose mass is independent of N. This predicts the existence of branes which stay light even when the dilaton decreases. We show that, on the gravity side, these states originate from D2-D0 bound states wrapping the vanishing two-cycle of a conifold singularity that develops at large N.