Flips for spaces of quadrics on del Pezzo varieties
Abstract
For a cubic hypersurface X, work of Galkin--Shinder and Voisin shows the existence of a birational map relating the Hilbert scheme of two points X[2] with a certain projective bundle over X. Belmans--Fu--Raedschelders show that this is a standard flip, a particularly nice type of birational map inducing decompositions of derived categories. We show that this geometric construction extends to produce standard flips for Hilbert schemes of quadrics on various higher-dimensional del Pezzo varieties of degree at least 3, including cubics, intersections of two quadrics, and linear sections of Gr(2, 5). The resulting construction also generalizes results of Chung--Hong--Lee for quintic del Pezzo varieties. As an application, we produce a conjectural semiorthogonal decompositions for orthogonal Grassmannians of lines.