Equivariant Contact Darboux Quotients and Perversely Categorified Legendrian Correspondences

Abstract

Prior work has shown that shifted contact derived Artin stacks admit smooth Darboux atlases. However, establishing enumerative invariants and linearizing these categorical structures requires equivariant local models. We establish an equivariant Darboux theorem for $-1$-shifted contact derived Artin stacks. We prove that, in the smooth topology, these stacks admit smooth atlases by the derived contact Darboux scheme $\Delta\mathrm{loc}(s)$ associated to the derived discriminant locus of a relative section $s$. In the presence of reductive stabilizers $G$, this refines to the equivariant geometric quotient stack $[\Delta\mathrm{loc}(s)/G]$. By applying the BBDJS minimal model to the derived symplectification and descending algebraically along the structural free $\mathbb{G}_m$-action, we construct an $\ell$-adic perverse sheaf on any oriented $-1$-shifted contact stack. We utilize Verdier's specialization equivalence for monodromic sheaves to equip this perverse sheaf with a tame geometric monodromy automorphism $T$. This structure allows for the extraction of derived enumerative invariants via the $\ell$-adic Grothendieck-Lefschetz trace, thereby resolving the issue of generic topological acyclicity. The content of the other main results in this paper relies on a prior work, in which we have shown that derived intersections of $n$-shifted Legendrians yield $(n-1)$-shifted contact stacks and formulated the non-linear 2-categories of Legendrians $\mathcal{F}_c(X)$ and $Leg_n$. Using this geometric setup, we formulate in this paper a contact analogue of Joyce's conjecture to linearize these structures. We then construct the categorified Legendrian 2-categories $\mathfrak{L}\mathcal{F}c(X)$ and $LLeg_0$ via $\ell$-adic Fourier-Mukai pull-push functors, connecting the study of derived contact moduli spaces to microlocal sheaf theory.