Confinement in Five Dimensions

Five dimensional super conformal field theories can be studied using their geometric realisation as a limit of $M$-theory on a metrically conical Calabi-Yau threefold. We utilise this framework to investigate the phases of such theories that arise by varying the couplings away from the conformal point. We demonstrate that many 5d SCFTs, including strongly coupled gauge theories, have couplings giving rise to massive, confining vacua with confining strings and corresponding unbroken 1-form symmetries. The simplest examples arise by considering the parameter space of {\it complete} Ricci flat metrics on discrete quotients of the standard conifold singularity. Varying other couplings produces coupled 5d SCFTs interacting via massive BPS instanton particle states.