5-brane webs, symmetry enhancement, and duality in 5d supersymmetric gauge theory

We present a number of investigations of 5d $ \mathcal{N} $ = 1 supersymmetric gauge theories that make use of 5-brane web constructions and the 5d superconformal index. These include an observation of enhanced global symmetry in the 5d fixed point theory corresponding to SU( N ) gauge theory with Chern-Simons level ±N , enhanced global symmetries in quiver theories, and dualities between quiver theories and non-quiver theories. Instanton contributions play a crucial role throughout