Gromov-Witten invariants of P^2-stacks

Abstract

The Gromov-Witten theory of Deligne-Mumford stacks is a recent development, and hardly any computations have been done beyond 3-point genus 0 invariants. This paper provides explicit recursions which, together with some invariants computed by hand, determine all genus 0 invariants of the stack P^2_{D,2}. Here D is a smooth plane curve and P^2_{D,2} is locally isomorphic to the stack quotient [U/(Z/(2))], where U -> V \subset P^2 is a double cover branched along D \cap V. The introduction discusses an enumerative application of these invariants.