On the Quantum Geometry of String Theory

TL;DR

This paper discusses how the IKKT matrix model, a candidate for a non-perturbative formulation of type IIB superstring theory, may dynamically generate lower-dimensional universes through the phase of the fermion determinant.

Contribution

It highlights the importance of the fermion determinant phase in the potential emergence of lower-dimensional space-times within the matrix model.

Findings

Phase of the fermion determinant influences space-time dimensionality

Lower-dimensional universes may dominate the model

Dynamical space-time reduction is possible

Abstract

The IKKT or IIB matrix model has been proposed as a non-perturbative definition of type IIB superstring theories. It has the attractive feature that space--time appears dynamically. It is possible that lower dimensional universes dominate the theory, therefore providing a dynamical solution to the reduction of space--time dimensionality. We summarize recent works that show the central role of the phase of the fermion determinant in the possible realization of such a scenario.