Divergence and quasimorphisms of right-angled Artin groups

We give a group theoretic characterization of geodesics with superlinear divergence in the Cayley graph of a right-angled Artin group A (I") with connected defining graph. We use this to prove that the divergence of A (I") is linear if I" is a join and quadratic otherwise. As an application, we give a complete description of the cut points in any asymptotic cone of A (I"). We also show that every non-abelian subgroup of A (I") has an infinite-dimensional space of non-trivial quasimorphisms.