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Improved harmonic approximation and the 2D Ising model at $T\neq T_{c}$ and $h\neq0$

Aníbal Iucci·Carlos M. Naón
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Abstract

We propose a new method to determine the unknown parameter associated to a self-consistent harmonic approximation. We check the validity of our technique in the context of the sine-Gordon model. As a non trivial application we consider the scaling regime of the 2D Ising model away from the critical point and in the presence of a magnetic field $h$. We derive an expression that relates the approximate correlation length $ξ$, $T-T_c$ and $h$.

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Aníbal Iucci, Carlos M. Naón. 2002-09-02. Improved harmonic approximation and the 2D Ising model at $T\neq T_{c}$ and $h\neq0$. https://doi.org/10.1088/0305-4470%2F35%2F38%2F304

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