Large deviations analysis for random combinatorial partitions with counter terms

TL;DR

This paper analyzes large deviations in random combinatorial partitions, focusing on models with counter terms, revealing critical behavior and phase transitions, especially in the Huang-Yang-Luttinger model.

Contribution

It provides a comprehensive large deviation analysis of models with counter terms, including the HYL model, highlighting critical phenomena and phase transition behavior.

Findings

Critical parameter existence with multiple minimizers

Identification of phase transition in the HYL model

Extension of order parameter concept for diverging cycle lengths

Abstract

In this paper, we study various models for random combinatorial partitions using large deviation analysis for diverging scale of the reference process. Scaling limits of similar models have been studied recently \cite{FSa,FSb} going back to \cite{Ver96}. After studying the reference model, we provide a complete analysis of two mean field models, one of which is well-know \cite{BCMP05} and the other one is the cycle mean field model. Both models show critical behaviour despite their rate functions having unique minimiser. The main focus is then a model with negative counter term, the probabilistic version of the so-called \emph{Huang-Yang-Luttinger} (HYL) model \cite{BLP}. Criticality in this model is the existence of a critical parameter for which two simultaneous minimiser exists. At criticality an order parameter is introduced as the double limits for the density of cycles with diverging length, and as such it extends recent work \cite{AD21}.