Recent developments in the type IIB matrix model

TL;DR

This paper reviews recent progress in the type IIB matrix model, highlighting its potential to explain spontaneous symmetry breaking and the emergence of a 3+1 dimensional universe, with implications for cosmology.

Contribution

It summarizes recent findings on the Euclidean and Lorentzian versions of the model, including symmetry breaking and universe emergence, advancing understanding of nonperturbative superstring theory.

Findings

SO(10) symmetry is spontaneously broken in the Euclidean model

A (3+1)-dimensional universe emerges dynamically in the Lorentzian model

Exponential and power-law expansions are observed at different times

Abstract

We review recent developments in the type IIB matrix model, which was conjectured to be a nonperturbative formulation of superstring theory. In the first part we review the recent results for the Euclidean model, which suggest that SO(10) symmetry is spontaneously broken. In the second part we review the recent results for the Lorentzian model. In particular, we discuss Monte Carlo results, which suggest that (3+1)-dimensional expanding universe emerges dynamically. We also discuss some results suggesting the emergence of exponential expansion and the power-law expansion at later times. The behaviors at much later times are studied by the classical equation of motion. We discuss a solution representing 3d expanding space, which suggests a possible solution to the cosmological constant problem.