A structure theorem for Harish-Chandra bimodules via coinvariants and Golod rings

We consider the category of Harish-Chandra bimodules for a semisimple complex Lie algebra. We describe algebras of self-extensions of certain simple objects by showing that their blocks are equivalent to module categories over complete intersections or Golod rings. Our main result is a generalisation of Soergelʹs structural description of the blocks of category O to a description of the general integral blocks of Harish-Chandra bimodules.