Critical dimension and negative specific heat in one-dimensional large- N reduced models

Abstract

We investigate critical phenomena of the Yang-Mills (YM) type one-dimensional matrix model that is a large-N reduction (or dimensional reduction) of the D+1 dimensional U(N) pure YM theory (bosonic Banks-Fischler-Shenker-Susskind model). This model shows a large-N phase transition at finite temperature, which is analogous to the confinement/deconfinement transition of the original YM theory. We study the matrix model at a three-loop calculation via the "principle of minimum sensitivity" and find that there is a critical dimension D=35.5: At D≤35, the transition is of first order, while it is of second order at D≥36. Furthermore, we evaluate several observables in our method, and they nicely reproduce the existing Monte Carlo results. Through the gauge/gravity correspondence, the transition is expected to be related to a Gregory-Laflamme transition in gravity, and we argue that the existence of the critical dimension is qualitatively consistent with it. Besides, in the first order transition case, a stable phase having negative specific heat appears in the microcanonical ensemble, which is similar to Schwarzschild black holes. We study some properties of this phase.