To each right-angled Artin group $A_\Gamma$ there is an associated space $S_\Gamma$ on which the group acts on (the Salvetti complex). The fundamental group of the Salvetti complex is the right-angled Artin group itself $\pi_1(S_\Gamma)=A_\Gamma$.
Is $A_\Gamma$ always a CAT(0) group? Is this because the universal cover of $S_\Gamma$ is simply connected?
Let $\Gamma$ be a finite graph. Then the associated Salvetti complex $S_{\Gamma}$ is naturally a finite cube complex. Furthermore, Gromov's condition on the link is easy to verify, so that $S_{\Gamma}$ is a non-positively curved cube complex. Finally, we deduce that the universal covering $\widetilde{S}_{\Gamma}$ is a CAT(0) cube complex on which the right-angled Artin group $A_{\Gamma}$ acts geometrically: $A_{\Gamma}$ is CAT(0).
If $\Gamma$ is an infinite graph, then $A_{\Gamma}$ is not finitely-generated and cannot be CAT(0).