Intersection cohomology of moduli spaces of sheaves on surfaces
  We study intersection cohomology of moduli spaces of semistable vector bundles on a complex algebraic surface. Our main result relates intersection Poincare polynomials of the moduli spaces to Donaldson-Thomas invariants of the surface. In support of this result, we compute explicitly intersection Poincare polynomials for sheaves with rank two and three on ruled surfaces. 
Jan Manschot and Sergey Mozgovoy
math.AG hep-th