Yehao Zhou:Stable envelope for critical loci, and application to shifted Yangians

Abstract: In this talk we will introduce a generalization of Maulik-Okounkov’s stable envelopes to equivariant critical cohomology. In the case of a tripled quiver variety with standard cubic potential, this reduces to MO’s stable envelope for the Nakajima variety of the corresponding doubled quiver along the dimensional reduction. We define non-abelian stable envelopes for quivers with potentials following a similar construction of Aganagic-Okounkov, and use them to relate critical COHAs to the abelian stable envelopes. RTT formalism leads to natural (shifted) (super) Yangian action on the critical cohomology of quiver varieties with potentials. This talk is based on joint work with Yalong Cao, Andrei Okounkov, and Zijun Zhou.