The effects of quantum instantons on the thermodynamics of the CP^(N-1) model
arXiv:hep-th/0602082 · doi:10.1103/PhysRevD.74.045028
Abstract
Using the 1/N expansion, we study the influence of quantum instantons on the thermodynamics of the CP^(N-1) model in 1+1 dimensions. We do this by calculating the pressure to next-to-leading order in 1/N, without quantum instanton contributions. The fact that the CP^1 model is equivalent to the O(3) nonlinear sigma model, allows for a comparison to the full pressure up to 1/N^2 corrections for N=3. Assuming validity of the 1/N expansion for the CP^1 model makes it possible to argue that the pressure for intermediate temperatures is dominated by the effects of quantum instantons. A similar conclusion can be drawn for general N values by using the fact that the entropy should always be positive.
7 pages, 5 figures, revtex. To appear in PRD. Some arguments and conclusions reformulated