Bulk geometry in gauge/gravity duality and color degrees of freedom

U(N) supersymmetric Yang-Mills theory naturally appears as the low-energy effective theory of a system of N D-branes and open strings between them. Transverse spatial directions emerge from scalar fields, which are N x N matrices with color indices; roughly speaking, the eigenvalues are the locations of D-branes. In the past, it was argued that this simple emergent space picture cannot be used in the context of gauge/gravity duality, because the ground-state wave function delocalizes at large N, leading to a conflict with the locality in the bulk geometry. In this paper, we show that this conventional wisdom is not correct: the ground-state wave function does not delocalize, and there is no conflict with the locality of the bulk geometry. This conclusion is obtained by clarifying the meaning of the diagonalization of a matrix in Yang-Mills theory, which is not as obvious as one might think. This observation opens up the prospect of characterizing the bulk geometry via the color degrees of freedom in Yang-Mills theory, all the way down to the center of the bulk.

Automated summary

This paper reveals that the previous notion that the ground-state wave function delocalizes at large N and conflicts with the locality of bulk geometry is incorrect. By clarifying the meaning of matrix diagonalization in Yang-Mills theory, it opens up the possibility of characterizing bulk geometry through the color degrees of freedom in Yang-Mills theory all the way to the center of the bulk.