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Scalar O(N) Model at Finite Temperature -- 2PI Effective Potential in Different Approximations

Jurgen Baacke·Stefan Michalski
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Abstract

We calculate the two-particle irreducible (2PI) effective potential of the O(N) linear sigma model in 1+1 dimensions. The approximations we use are the next-to-leading order of a 1/N expansion (for arbitrary N) and a kind of "resummed loop approximation" for N=1. We show that the effective potential of the 1/N expansion is convex for N=4 and N=10 whereas it is not for the "loop" expansion and the case N=1 of the 1/N expansion.

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Jurgen Baacke, Stefan Michalski. 2004-09-14. Scalar O(N) Model at Finite Temperature -- 2PI Effective Potential in Different Approximations. https://doi.org/10.1142/9789812702159_0063

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