### Abstract

We study the critical behavior for inhomogeneous versions of the Curie-Weiss model, where the coupling constant J_{ij}(β) for the edge ij on the complete graph is given by J_{ij}(β) = βw_{i}w_{j}/ (∑ _{k∈[N]}w_{k}). We call the product form of these couplings the rank-1 inhomogeneous Curie-Weiss model. This model also arises [with inverse temperature β replaced by sinh (β) ] from the annealed Ising model on the generalized random graph. We assume that the vertex weights (wi)i∈[N] are regular, in the sense that their empirical distribution converges and the second moment converges as well. We identify the critical temperatures and exponents for these models, as well as a non-classical limit theorem for the total spin at the critical point. These depend sensitively on the number of finite moments of the weight distribution. When the fourth moment of the weight distribution converges, then the critical behavior is the same as on the (homogeneous) Curie-Weiss model, so that the inhomogeneity is weak. When the fourth moment of the weights converges to infinity, and the weights satisfy an asymptotic power law with exponent τ with τ∈ (3 , 5) , then the critical exponents depend sensitively on τ. In addition, at criticality, the total spin S_{N} satisfies that S_{N}/ N^{(τ-2)/(τ-1)} converges in law to some limiting random variable whose distribution we explicitly characterize.

Original language | English |
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Pages (from-to) | 221-263 |

Number of pages | 43 |

Journal | Communications in Mathematical Physics |

Volume | 348 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1 Nov 2016 |

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## Cite this

*Communications in Mathematical Physics*,

*348*(1), 221-263. https://doi.org/10.1007/s00220-016-2752-2