New characterizations of Muckenhoupt $A_p$ distance weights for $p>1$

Abstract

We characterize the collection of sets $E \subset \mathbb{R}^n$ for which there exists $\theta \in \mathbb{R}\setminus\{0\}$ such that the distance weight $w(x) = \operatorname{dist}(x, E)^\theta$ belongs to the Muckenhoupt class $A_p$, where $p > 1$. These sets exhibit a certain balance between the small-scale and large-scale pores that constitute their complement$-$a property we show to be more general than the so-called weak porosity condition, which in turn, and according to recent results, characterizes the sets with associated distance weights in the $A_1$ case. Furthermore, we verify the agreement between this new characterization and the properties of known examples of distance weights, that are either $A_p$ weights or merely doubling weights, by means of a probabilistic approach that may be of interest by itself.