2020/06/01 by Jun Nishimura, Nishimura, Jun
Mathematics · #Advanced Algebra and Geometry #Advanced Topics in Algebra #Algebraic structures and combinatorial models #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Theory (hep-th)
paper · pdf · doi:10.48550/arxiv.2006.00768
openalex publication_date 2020/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The type IIB matrix model is a promising candidate for a nonperturbative\nformulation of superstring theory. In the Lorentzian version, in particular,\nthe emergence of (3+1)D expanding space-time was observed by Monte Carlo\nstudies of this model. Here we provide new perspectives on the (3+1)D expanding\nspace-time that have arised from recent studies. First it was found that the\nmatrix configurations generated by the simulation are singular in that the\nsubmatrices representing the expanding 3D space have only two large eigenvalues\nassociated with the Pauli matrices. This problem was conjectured to occur due\nto the approximation used to avoid the sign problem in simulating the model. In\norder to confirm this conjecture, the complex Langevin method was applied to\novercome the sign problem instead of using the approximation. The results\nindeed showed a clear departure from the Pauli-matrix structure, while the\n(3+1)D expanding behavior remained unaltered. It was also found that classical\nsolutions obtained within a certain ansatz show quite generically a (3+1)D\nexpanding behavior with smooth space-time structure.\n