On cubic arc-transitive k-multicirculants with soluble groups

A finite simple graph is called a k-multicirculant if its automorphism group contains a cyclic semiregular subgroup having k orbits on the vertex set. It was shown by Giudici et al. that, if k is squarefree and coprime to 6, then a cubic arc-transitive k-multicirculant has at most $$6k^2$$ vertices (J. Combin. Theory Ser. B, 2017). In this paper, we classify the latter graphs under the assumption that their semiregular cyclic subgroups are contained in a soluble group of automorphisms acting transitively on the arc set of the graphs. As an application, cubic arc-transitive p-multicirculants are completely described for each odd prime p.