On the Refined Symplectic Sum Formula for Gromov-Witten Invariants
  We describe the extent to which Ionel-Parker's proposed refinement of the standard relative Gromov-Witten invariants sharpens the usual symplectic sum formula. The key product operation on the target spaces for the refined invariants is specified in terms of abelian covers of symplectic divisors, making it suitable for studying from a topological perspective. We give several qualitative applications of this refinement, which include vanishing results for Gromov-Witten invariants. 
Mohammad F. Tehrani and Aleksey Zinger
math.SG math.AG