Rationality of A1-connected smooth proper varieties in higher dimensions

Determine whether every A1-connected smooth proper variety of dimension greater than two is rational.

Background

The paper establishes that a smooth proper A1-connected surface over an algebraically closed field of characteristic zero is rational. It also notes that A1-connectedness implies vanishing of unramified cohomology groups, including the Brauer group, but these consequences do not currently settle rationality in higher dimensions. The unresolved question is whether A1-connectedness is sufficiently strong to force rationality for smooth proper varieties beyond the surface case.

References

In higher dimensions it is not known whether an A1-connected, smooth, proper variety is rational.

— Rationality of varieties and $\mathbb{A}^1$-homotopy theory  (2610.03680 - Choudhury et al., 2 Oct 2026) in Remark 3.11, p. 10