Critical properties of a dilute O($n$) model on the kagome lattice

TL;DR

This paper analytically and numerically investigates the critical properties of a dilute O(n) model on the kagome lattice, revealing its connection to the Potts model and identifying a line of multicritical points with universal properties.

Contribution

The paper establishes an exact mapping between the dilute O(n) model on the kagome lattice and the critical q-state Potts model, enabling the determination of critical points and properties.

Findings

Identifies a branch of critical points for the dilute O(n) model on the kagome lattice.

Shows the model reproduces known universal properties at n=0 (polymer collapse).

Finds a line of multicritical points with universal behavior similar to that on the square lattice.

Abstract

A critical dilute O($n$) model on the kagome lattice is investigated analytically and numerically. We employ a number of exact equivalences which, in a few steps, link the critical O($n$) spin model on the kagome lattice to the exactly solvable critical $q$-state Potts model on the honeycomb lattice with $q=(n+1)^2$. The intermediate steps involve the random-cluster model on the honeycomb lattice, and a fully packed loop model with loop weight $n'=\sqrt{q}$ and a dilute loop model with loop weight $n$, both on the kagome lattice. This mapping enables the determination of a branch of critical points of the dilute O($n$) model, as well as some of its critical properties. For $n=0$, this model reproduces the known universal properties of the $\theta$ point describing the collapse of a polymer. For $n\neq 0$ it displays a line of multicritical points, with the same universal properties as a branch of critical behavior that was found earlier in a dilute O($n$) model on the square lattice. These findings are supported by a finite-size-scaling analysis in combination with transfer-matrix calculations.