Phase diagrams of the multitrace quartic matrix models of noncommutative Φ^4

Abstract: We report a direct and robust calculation, free from ergodic problems, of the non-uniform-to-uniform (stripe) transition line of noncommutative $\Phi^4_2$ by means of an exact Metropolis algorithm applied to the first non-trivial multitrace correction of this theory on the fuzzy sphere. In fact, we reconstruct the entire phase diagram including the Ising, matrix and stripe boundaries together with the triple point. We also report that the measured critical exponents of the Ising transition line agrees with the Onsager values in two dimensions. The triple point is identified as a termination point of the one-cut-to-two-cut transition line and is located at $(\tilde{b},\tilde{c})=(-1.55,0.4)$ which compares favorably with previous Monte Carlo estimate.