Introduction to a provisional mathematical definition of Coulomb   branches of $3$-dimensional $\mathcal N=4$ gauge theories
  This is an introduction to a provisional mathematical definition of Coulomb branches of $3$-dimensional $\mathcal N=4$ supersymmetric gauge theories, studied in arXiv:1503.03676, arXiv:1601.03586 
Hiraku Nakajima
math.RT hep-th math.AG math.DG math.QA