Jacopo Borga - Exponents for directed distances in planar maps in λ\gammaλ-LQG universality class
Presenter
January 29, 2026
Abstract
Recorded 29 January 2026. Jacopo Borga of the Massachusetts Institute of Technology presents "Exact exponents for directed distances in planar maps in the λ\gammaλ-LQG universality class for λ\gamma\in(0, \sqrt{4/3}]λ" at IPAM's New Interactions Between Probability and Geometry Workshop.
Abstract: We study a natural one-parameter family of random bipolar-oriented planar maps which lies in the γ
-Liouville quantum gravity (LQG) universality class for γ∈(0,4/3−−−√]
. For these maps, we identify exact scaling exponents for directed graph distances. Writing n
for the size of the map, the longest directed paths have lengths comparable to n2/(4−γ2)
(up to constants), while the shortest directed paths have lengths of order n2/(4+γ2)
(up to constants). These exponents give the scaling dimensions of discretizations of the conjectural γ
-directed LQG metrics for γ∈(0,4/3−−−√]
. These results are obtained by analyzing the local limit, denoted by γ
-UIBOT, of these maps around a typical edge. We construct the Busemann function, which measures directed distances to infinity along a natural interface in the γ
-UIBOT. We show that in the case of longest (resp.\ shortest) directed paths, this Busemann function converges in the scaling limit to a (1−γ2/4)
-stable Lévy process (resp.\ a (1+γ2/4)
-stable Lévy process). Based on joint work with E. Gwynne.
Learn more online at: https://www.ipam.ucla.edu/programs/workshops/new-interactions-between-probability-and-geometry/?tab=overview