Minimal volume entropy of free-by-cyclic groups and 2-dimensional right-angled Artin groups

Abstract

Let $G$ be a free-by-cyclic group or a 2-dimensional right-angled Artin group. We provide an algebraic and a geometric characterization for when each aspherical simplicial complex with fundamental group isomorphic to $G$ has minimal volume entropy equal to 0. In the nonvanishing case, we provide a positive lower bound to the minimal volume entropy of an aspherical simplicial complex of minimal dimension for these two classes of groups. Our results rely upon a criterion for the vanishing of the minimal volume entropy for 2-dimensional groups with uniform uniform exponential growth. This criterion is shown by analyzing the fiber ${\pi }_1$-growth collapse and non-collapsing assumptions of Babenko-Sabourau.

25 pages, 2 figures; v2: corrected error in statement and proof of Theorem 3.3, main results unchanged