Instantons, symmetries and anomalies in five dimensions

All five-dimensional non-abelian gauge theories have a $U(1)_I$ global symmetry associated with instantonic particles. We describe an obstruction to coupling classical background field that occurs whenever the theory has one-form center symmetry. This is finite-order mixed 't Hooft anomaly between two symmetries. also show similar takes place in fundamental matter by studying twisted bundles for ordinary flavor explore some general dynamical properties of candidate phases implied anomaly. Finally, we apply our results supersymmetric five dimensions and analyze enhancement patterns occurring at their conjectured RG fixed points.