The emergence of expanding space-time in the Lorentzian type IIB matrix model with a novel regularization

TL;DR

This paper demonstrates that adding a Lorentz invariant mass term and using complex Langevin simulations to address the sign problem leads to the emergence of expanding Lorentzian space-time in the Lorentzian type IIB matrix model, a candidate for superstring theory.

Contribution

The study introduces a Lorentz invariant mass term as an IR regulator and applies complex Langevin simulations to show emergent expanding space-time in the model.

Findings

Emergence of Lorentzian space-time with expansion

Use of complex Langevin to handle sign problem

Mass term acts as an effective IR regulator

Abstract

The Lorentzian type IIB matrix model is a promising candidate for a non-perturbative formulation of superstring theory. However, it was recently found that a Euclidean space-time appears in the conventional large-$N$ limit. In this work, we study the model with a Lorentz invariant mass term which can be considered as an IR regulator. By performing complex Langevin simulations to overcome the sign problem, we observe the emergence of expanding space-time with Lorentzian signature.