Degenerations in graded quiver varieties and in derived categories of Dynkin quivers

For any acyclic quiver, Keller-Scherotzke provided a stratifying functor from the category of finite-dimensional modules of the singular Nakajima category to the derived category of the quiver. Under this functor, a degeneration of strata of a graded quiver variety corresponds to a degeneration, in the sense of Jensen-Su-Zimmermann, in the derived category. In this article, for any Dynkin quiver, we further investigate Jensen-Su-Zimmermann’s partial order and show that any degeneration of objects in the derived category can be obtained in this way.