Excursion theory for Brownian motion indexed by the Brownian tree
Journal of the European Mathematical Society, Tome 20 (2018) no. 12, pp. 2951-3016
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We develop an excursion theory for Brownian motion indexed by the Brownian tree, which in many respects is analogous to the classical Itô theory for linear Brownian motion. Each excursion is associated with a connected component of the complement of the zero set of the tree-indexed Brownian motion. Each such connected component is itself a continuous tree, and we introduce a quantity measuring the length of its boundary. The collection of boundary lengths coincides with the collection of jumps of a continuous-state branching process with branching mechanism ψ(u)=8/3u3/2. Furthermore, conditionally on the boundary lengths, the different excursions are independent, and we determine their conditional distribution in terms of an excursion measure M0 which is the analog of the Itô measure of Brownian excursions. We provide various descriptions of M0, and we also determine several explicit distributions, such as the joint distribution of the boundary length and the mass of an excursion under M0. We use the Brownian snake as a convenient tool for defining and analysing the excursions of our tree-indexed Brownian motion.
Classification :
60-XX
Keywords: Excursion theory, tree-indexed Brownian motion, continuum random tree, Brownian snake, exit measure, continuous-state branching process
Keywords: Excursion theory, tree-indexed Brownian motion, continuum random tree, Brownian snake, exit measure, continuous-state branching process
@article{JEMS_2018_20_12_a1,
author = {C\'eline Abraham and Jean-Fran\c{c}ois Le Gall},
title = {Excursion theory for {Brownian} motion indexed by the {Brownian} tree},
journal = {Journal of the European Mathematical Society},
pages = {2951--3016},
publisher = {mathdoc},
volume = {20},
number = {12},
year = {2018},
doi = {10.4171/jems/827},
url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/827/}
}
TY - JOUR AU - Céline Abraham AU - Jean-François Le Gall TI - Excursion theory for Brownian motion indexed by the Brownian tree JO - Journal of the European Mathematical Society PY - 2018 SP - 2951 EP - 3016 VL - 20 IS - 12 PB - mathdoc UR - http://geodesic.mathdoc.fr/articles/10.4171/jems/827/ DO - 10.4171/jems/827 ID - JEMS_2018_20_12_a1 ER -
%0 Journal Article %A Céline Abraham %A Jean-François Le Gall %T Excursion theory for Brownian motion indexed by the Brownian tree %J Journal of the European Mathematical Society %D 2018 %P 2951-3016 %V 20 %N 12 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4171/jems/827/ %R 10.4171/jems/827 %F JEMS_2018_20_12_a1
Céline Abraham; Jean-François Le Gall. Excursion theory for Brownian motion indexed by the Brownian tree. Journal of the European Mathematical Society, Tome 20 (2018) no. 12, pp. 2951-3016. doi: 10.4171/jems/827
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