On Landau-Ginzburg models for quadrics and flat sections of Dubrovin connections

Abstract: This paper proves a version of mirror symmetry expressing the (small) Dubrovin connection for even-dimensional quadrics in terms of a mirror-dual Landau-Ginzburg model (Xcan,W). Here Xcan is the complement of an anticanonical divisor in a Langlands dual quadric. The superpotential W is a regular function on Xcan and is written in terms of coordinates which are naturally identified with a cohomology basis of the original quadric. This superpotential is shown to extend the earlier Landau-Ginzburg model of Givental, and to be isomorphic to the Lie-theoretic mirror introduced by Rietsch. We also introduce a Laurent polynomial superpotential which is the restriction of W to a particular torus in Xcan. Together with results of Pech-Rietsch for odd quadrics, we obtain a combinatorial model for the Laurent polynomial superpotential in terms of a quiver, in the vein of those introduced in the 1990's by Givental for type A full flag varieties. These Laurent polynomial superpotentials form a single series, despite the fact that our mirrors of even quadrics are defined on dual quadrics, while the mirror to an odd quadric is naturally defined on a projective space. Finally, we express flat sections of the (dual) Dubrovin connection in a natural way in terms of oscillating integrals associated to (Xcan,W) and compute explicitly a particular flat section.