Capacity of the Range of Branching Random Walks in Low Dimensions

Consider a branching random walk $(V_u)_{u\in \mathcal T^{\mathrm{IGW}}}$ in $\mathbb Z^d$ with the genealogy tree $\mathcal T^{\mathrm{IGW}}$ formed by a sequence of i.i.d. critical Galton–Watson trees. Let $R_n$ be the set of points in $\mathbb Z^d$ visited by $(V_u)$ when the index $u$ explores the first $n$ subtrees in $\mathcal T^{\mathrm{IGW}}$. Our main result states that for $d\in \{3,4,5\}$, the capacity of $R_n$ is almost surely equal to $n^{(d-2)/{2}+o(1)}$ as $n\to \infty$.