Laplace operators on the cone of Radon measures

Abstract

We consider the infinite-dimensional Lie group $\mathfrak{G}$ which is the semidirect product of the group of compactly supported diffeomorphisms of a Riemannian manifold $X$ and the commutative multiplicative group of functions on $X$. The group $\mathfrak{G}$ naturally acts on the space $\mathbb{M}(X)$ of Radon measures on $X$. We would like to define a Laplace operator associated with a natural representation of $\mathfrak{G}$ in $L^2(\mathbb{M}(X),\mu )$. Here $\mu$ is assumed to be the law of a measure-valued Lévy process. A unitary representation of the group cannot be determined, since the measure $\mu$ is not quasi-invariant with respect to the action of the group $\mathfrak{G}$. Consequently, operators of a representation of the Lie algebra and its universal enveloping algebra (in particular, a Laplace operator) are not defined. Nevertheless, we determine the Laplace operator by using a special property of the action of the group $\mathfrak{G}$ (a partial quasi-invariance). We further prove the essential self-adjointness of the Laplace operator. Finally, we explicitly construct a diffusion process on $\mathbb{M}(X)$ whose generator is the Laplace operator.

References in corpus (3)

• Non-equilibrium stochastic dynamics in continuum: The free case
• The heat semigroup on configuration spaces
• Equilibrium diffusion on the cone of discrete Radon measures