# KEK Theory workshop 2018

17-20 December 2018
Kenkyu-Honkan bldg. 1F
Japan timezone
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# Contribution

Kenkyu-Honkan bldg. 1F - Kobayashi Hall

# On the emergence of (3+1)-dimensional expanding space-time in the Lorentzian type IIB matrix model (II)

## Speakers

• Mr. Mitsuaki HIRASAWA

## Description

The type IIB matrix model has been studied as a non-perturbative formulation of superstring theory. In particular, by Monte Carlo simulation of the Lorentzian type IIB matrix model, (3+1)-dimensional expanding space-time was shown to emerge dynamically. Moreover, from simulations of simplified models, it was suggested that the expansion of space is exponential at early times and it turns into a power-law at later times. This behavior is reminiscent of the inflation and the FRW universe in the radiation dominant era, respectively. In this work  we investigate the space-time structure of the matrix configurations generated by the simulation and find that the 3-dimensional space is essentially described by the Pauli matrices. We attribute this problem to the approximation used to avoid the sign problem in Monte Carlo simulation and discuss the possibility that a regular 3-dimensional space emerges if we simulate the model without such an approximation.