Complex Langevin studies of the emergent space-time in the type IIB matrix model

The type IIB matrix model has been proposed as a non-perturbative definition of superstring theory since 1996. We study a simplified model that describes the late time behavior of the type IIB matrix model non-perturbatively using Monte Carlo methods, and we use the complex Langevin method to overcome the sign problem. We investigate a scenario where the space-time signature changes dynamically from Euclidean at early times to Lorentzian at late times. We discuss the possibility of the emergence of the (3+1)D expanding universe.
Comment: 10 pages, 5 figures, contribution to the proceedings of East Asia Joint Symposium on Fields and Strings 2021 at Osaka City University, Nov. 22-27, 2021, minor corrections (v2)