The Emergent M-theory Limit

TL;DR

This paper explores the emergence of M-theory at infinite distance limits in moduli space, identifying the fundamental degrees of freedom as bound states of branes and Kaluza-Klein modes, extending the understanding of string dualities.

Contribution

It proposes a novel interpretation of emergent degrees of freedom in M-theory limit, highlighting bound states of M2- and M5-branes with Kaluza-Klein momentum.

Findings

For type IIB, D1-brane excitations are the light towers of states.

For type IIA, bound states of M2- and M5-branes with KK momentum emerge.

The inclusion of all these states is crucial for a quantum M-theory formulation.

Abstract

It has been recently proposed that at each infinite distance limit in the moduli space of quantum gravity a perturbative description emerges with fundamental degrees of freedom given by those infinite towers of states whose typical mass scale is parametrically not larger than the ultraviolet cutoff, identified with the species scale. This proposal is applied to the familiar ten-dimensional type IIA and IIB superstring theories, when considering the limit of infinite string coupling. For type IIB, the light towers of states are given by excitations of the D1-brane, as expected from self-duality. Instead, for type IIA at strong coupling, which is dual to M-theory on $S^1$, we make the observation that the emergent degrees of freedom are bound states of transversal M2- and M5-branes with Kaluza-Klein momentum along the circle. We speculate on the interpretation of the necessity of including all these states for a putative quantum formulation of M-theory.