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arXiv · hep-th/9712126

Vacuum structure of CP^N sigma models at theta=pi

M. Asorey·F. Falceto
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Abstract

We show that parity symmetry is not spontaneously broken in the CP^N sigma model for any value of N when the coefficient of the $θ$--term becomes $θ=π$ (mod $2π$). The result follows from a non-perturbative analysis of the nodal structure of the vacuum functional $ψ_0(z)$. The dynamical role of sphalerons turns out to be very important for the argument. The result introduces severe constraints on the possible critical behavior of the models at $θ=π$ (mod $2π$).

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M. Asorey, F. Falceto. 1997-12-12. Vacuum structure of CP^N sigma models at theta=pi. https://doi.org/10.1103/physrevlett.80.234

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