Diffusive scaling limit of the Busemann process in Last Passage Percolation

Abstract

In exponential last passage percolation, we consider the rescaled Busemann process $x\mapsto N^{-1/3}{B}_{0,[x{N}^{2/3}]e_1}^{\rho }(x\in \mathbb{R})$, as a process parametrized by the scaled density $\rho =1/2+\frac{\mu }{4}{N}^{-1/3}$, and taking values in $C(\mathbb{R})$. We show that these processes, as $N\to \infty$, have a càdlàg scaling limit $G=(G_{\mu }{)}_{\mu \in \mathbb{R}}$, parametrized by $\mu$ and taking values in $C(\mathbb{R})$. The limiting process $G$, which can be thought of as the Busemann process under the KPZ scaling, can be described as an ensemble of "sticky" lines of Brownian regularity. We believe $G$ is the universal scaling limit of Busemann processes in the KPZ universality class. Our proof provides insight into this limiting behaviour by highlighting a connection between the joint distribution of Busemann functions obtained by Fan and Seppäläinen in arXiv:1808.09069, and a sorting algorithm of random walks introduced by O'Connell and Yor [32]

arXiv comment53 p. The proof for the convergence of the finite dimensional distributions is much shorter than in previous versions