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arXiv · math-ph/0612075

Realizability of point processes

T. Kuna·J. L. Lebowitz·E. R. Speer
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Abstract

There are various situations in which it is natural to ask whether a given collection of $k$ functions, $ρ_j(\r_1,...,\r_j)$, $j=1,...,k$, defined on a set $X$, are the first $k$ correlation functions of a point process on $X$. Here we describe some necessary and sufficient conditions on the $ρ_j$'s for this to be true. Our primary examples are $X=\mathbb{R}^d$, $X=\matbb{Z}^d$, and $X$ an arbitrary finite set. In particular, we extend a result by Ambartzumian and Sukiasian showing realizability at sufficiently small densities $ρ_1(\mathbf{r})$. Typically if any realizing process exists there will be many (even an uncountable number); in this case we prove, when $X$ is a finite set, the existence of a realizing Gibbs measure with $k$ body potentials which maximizes the entropy among all realizing measures. We also investigate in detail a simple example in which a uniform density $ρ$ and translation invariant $ρ_2$ are specified on $\mathbb{Z}$; there is a gap between our best upper bound on possible values of $ρ$ and the largest $ρ$ for which realizability can be established.

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BibTeXRIS

T. Kuna, J. L. Lebowitz, E. R. Speer. 2007-03-20. Realizability of point processes. https://doi.org/10.1007/s10955-007-9393-y

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