Categorical Webs and $S$-duality in 4d $\mathcal{N}=2$ QFT

Matteo Caorsi, Sergio Cecotti

We review the categorical approach to the BPS sector of a 4d $\mathcal{N}=2$ QFT, clarifying many tricky issues and presenting a few novel results. To a given $\mathcal{N}=2$ QFT o…