Speaker
Description
Line operators in a 4d holomorphic-topological theory assemble into a meromorphic braided tensor category. Using boundary conditions, one can engineer a fibre functor on such a category, and perform categorical reconstruction to extract a vertex quantum group, for which line operators are modules. Such algebras will have the structure of a 'chiral (relative) Drinfeld double'. For 4d N=2 theories in the HT-twist, we conjecturally recover the relevant cohomological Hall algebra as the positive half of what we call a 'BPS Yangian', which for simple examples we explicitly construct out of BPS states. Moreover, every algebra will come with a collection of chiral coproducts / R-matrices and Drinfeld twists between them. In turn, we obtain a physical interpretation of Drinfeld-deformed-type coproducts. This talk is based on joint work with Tudor Dimofte.