Thermodynamics of the QCD Plasma and the Large-N Limit

The equilibrium thermodynamic properties of the SU(N) plasma are studied nonperturbatively in the large-N limit, via high-precision lattice simulations at temperatures from 0.8T_c to 3.4T_c (T_c being the critical deconfinement temperature). Our results for SU(N) Yang-Mills theories with N=3, 4, 5, 6, and 8 colors show a very mild dependence on N, supporting the idea that the QCD plasma could be described by models based on the large-N limit. We compare our data with various theoretical descriptions, including, in particular, the improved holographic QCD model proposed by Kiritsis and collaborators. We also comment on the relevance of an AdS/CFT description in a phenomenologically interesting temperature range where the system, while still strongly coupled, becomes approximately scale invariant. Finally, we extrapolate our results to the N→∞ limit.