Application of large deviation theory to the mean-field <InlineEquation ID="Equ1"> <EquationSource Format="TEX">$\boldsymbol{\varphi}^\mathsf{4}$</EquationSource> </InlineEquation>-model

A large deviation technique is used to calculate the microcanonical entropy function s(v,m) of the mean-field ϕ<Superscript>4</Superscript>-model as a function of the potential energy v and the magnetization m. As in the canonical ensemble, a continuous phase transition is found. An analytical expression is obtained for the critical energy v<Subscript>c</Subscript>(J) as a function of the coupling parameter J. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006