Statistical Physics of the Polarised IKKT Matrix Model

Abstract

The polarised IKKT matrix model is the worldpoint theory of $N$ D-instantons in a background three-form flux of magnitude $\hat{I}\text{c◯}$, and promises to be a highly tractable model of holography. The matrix integral can be viewed as a statistical physics partition function with inverse temperature $\hat{I}{\text{c◯}}^4$. At large $\hat{I}\text{c◯}$ the model is dominated by a matrix configuration corresponding to a 'polarised' spherical D1-brane. We show that at a critical value of $\hat{I}{\text{c◯}}^{2}N$ the model undergoes a first order phase transition, corresponding to tunneling into a collection of well-separated D-instantons. These instantons are the remnant of a competing saddle in the high $\hat{I}\text{c◯}$ phase corresponding to spherical $(p,q)$ fivebranes. We use a combination of numerical and analytical arguments to capture the different regimes of the model.

21 pages and 8 figures. v2: references added. v3: appendix with finite N scaling added