publication . Preprint . 2021

Multiplicative chaos of the Brownian loop soup

Aïdékon, Élie; Berestycki, Nathanaël; Jego, Antoine; Lupu, Titus;
Open Access English
  • Published: 28 Jul 2021
  • Publisher: HAL CCSD
  • Country: France
Abstract
We construct a measure on the thick points of a Brownian loop soup in a bounded domain $D$ of the plane with given intensity $\theta>0$, which is formally obtained by exponentiating the square root of its occupation field. The measure is constructed via a regularisation procedure, in which loops are killed at a fix rate, allowing us to make use of the Brownian multiplicative chaos measures previously considered in [BBK94, AHS20, Jeg20a]. At the critical intensity $\theta = 1/2$, it is shown that this measure coincides with the hyperbolic cosine of the Gaussian free field, which is closely related to Liouville measure. This allows us to draw several conclusions which elucidate connections between Brownian multiplicative chaos, Gaussian free field and Liouville measure. For instance, it is shown that Liouville-typical points are of infinite loop multiplicity, with the relative contribution of each loop to the overall thickness of the point being described by the Poisson--Dirichlet distribution with parameter $\theta = 1/2$. Conversely, the Brownian chaos associated to each loop describes its microscopic contribution to Liouville measure. Along the way, our proof reveals a surprising exact integrability of the multiplicative chaos associated to a killed Brownian loop soup. We also obtain some estimates on the loop soup which may be of independent interest.
Comment: 103 pages, 1 figure
Subjects
free text keywords: Brownian loop soup, Brownian multiplicative chaos, Gaussian free field, Gaussian multiplicative chaos, Isomorphism theorems, Thick points, MSC2020: 60G15; 60G55; 60J55; 60J65; 81T27, [MATH.MATH-PR]Mathematics [math]/Probability [math.PR], Mathematics - Probability, Mathematical Physics
Related Organizations
Funded by
UKRI| EPSRC Centre for Doctoral Training in Analysis (Cambridge Centre for Analysis)
Project
  • Funder: UK Research and Innovation (UKRI)
  • Project Code: EP/L016516/1
  • Funding stream: EPSRC
,
FWF| Scaling limits in random conformal geometry
Project
  • Funder: Austrian Science Fund (FWF) (FWF)
  • Project Code: P 33083
  • Funding stream: Einzelprojekte
,
ANR| MALIN
Project
MALIN
Interacting Random Walks
  • Funder: French National Research Agency (ANR) (ANR)
  • Project Code: ANR-16-CE93-0003

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