The Open/Closed Gromov-Witten/Hurwitz Correspondence and Localized World Sheets for Completed Cycles
Jan Troost
TL;DR
The paper establishes a rigorous open/closed Gromov-Witten/Hurwitz duality by formulating a grand canonical open/closed orbifold theory based on the inverse monoid of partial permutations and its holonomy interpretation. It demonstrates that bulk operators in GW correspond to completed cycles in Hurwitz theory and shows that the large $n$ limit yields an isomorphism with shifted symmetric functions, thereby unifying open/closed sectors via relative invariants and boundary holonomies. Through explicit equivariant localization calculations on ${f P}^1$, the authors identify localized world sheets that contribute to completed-cycle terms and develop a diagrammatic framework (left-right factors, symmetry factors, cut-and-join interactions) to compute two-point and one-point functions, including relative correlators. The results include concrete checks of the degree/dimension constraints, oscillator representations, and linear Hodge integral manipulations (ELSV-type formulas), culminating in a coherent picture of completed cycles as localized world-sheet contributions. The work provides a tractable combinatorial and operator-theoretic approach to the open/closed GW/Hurwitz correspondence, with implications for higher-genus amplitudes, relative theories, and potential links to integrable hierarchies and holographic interpretations.
Abstract
We discuss the open/closed version of the Gromov-Witten/Hurwitz correspondence. The duality equates the relative Gromov-Witten invariants and the count of covers of the target space with prescribed holonomies at boundaries. We clarify the projective large N limit as well as the role of the completed versus the ordinary cycles associated to the bulk and the boundary vertex operators respectively. We provide an example check of both the correspondence and the fact that cycles dual to closed strings need to be completed. Moreover, we identify the connected world sheets that contribute to an equivariantly localized amplitude in the bulk that is solely due to a completion term. We also propose a picture for the completed cycle combinatorics that involves a localization diagram glued to a cut-and-join string interaction.
