Smooth models of motivic spheres and the clutching construction. (English) Zbl 1405.14050

Asok, Aravind; Doran, Brent; Fasel, Jean

Int. Math. Res. Not. 2017, No. 6, 1890-1925 (2017).

Summary: We study the representability of motivic spheres by smooth varieties. We show that certain explicit “split” quadric hypersurfaces have the \(\mathbb A^1\)-homotopy type of motivic spheres over the integers and that the \(\mathbb A^1\)-homotopy types of other motivic spheres do not contain smooth schemes as representatives. We then study some applications of these representability/non-representability results to the construction of new exotic \(\mathbb A^1\)-contractible smooth schemes. Then, we study vector bundles on even dimensional “split” quadric hypersurfaces by developing an algebro-geometric variant of the classical construction of vector bundles on spheres via clutching functions.

MSC:

14F42

Motivic cohomology; motivic homotopy theory