Nested closed paths in two-dimensional percolation

Abstract

For two-dimensional percolation on a domain with the topology of a disc, we introduce a nested-path operator (NP) and thus a continuous family of one-point functions $W_k \equiv \langle \mathcal{R} \cdot k^\ell \rangle $, where $\ell$ is the number of independent nested closed paths surrounding the center, $k$ is a path fugacity, and $\mathcal{R}$ projects on configurations having a cluster connecting the center to the boundary. At criticality, we observe a power-law scaling $W_k \sim L^{-X_\textsc{np}}$, with $L$ the linear system size, and we determine the exponent $X_\textsc{np}$ as a function of $k$. On the basis of our numerical results, we conjecture anvanalytical formula, $X_\textsc{np} (k) = \frac{3}{4}\phi^2 -\frac{5}{48}\phi^2/(\phi^2-\frac{2}{3})$ with $k = 2 \cos(\pi \phi)$, which reproduces the exact results for $k=0,1$ and agrees with the high-precision estimate of $X_\textsc{np}$ for other $k$ values. In addition, we observe that $W_2(L)=1$ for site percolation on the triangular lattice with any size $L$, and we prove this identity for all self-matching lattices.