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The effects of quantum instantons on the thermodynamics of the CP^(N-1) model

Jens O. Andersen·Daniel Boer·Harmen J. Warringa
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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.

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Jens O. Andersen, Daniel Boer, Harmen J. Warringa. 2006-08-07. The effects of quantum instantons on the thermodynamics of the CP^(N-1) model. https://doi.org/10.1103/physrevd.74.045028

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