English

A surface with representable $\text{CH}_{0}$-group but no universal zero-cycle

Algebraic Geometry 2026-03-10 v2 K-Theory and Homology

Abstract

We introduce a new obstruction to the existence of a universal 00-cycle on a smooth projective complex variety. As an application, we construct a smooth projective complex surface whose Chow group of 00-cycles is representable but which does not admit a universal 00-cycle. This provides a two-dimensional analogue of Voisin's recent threefold counterexample to a question of Colliot-Th\'el\`ene. As a further consequence, we exhibit the first example of a smooth projective threefold of Kodaira dimension zero carrying a non-torsion Hodge class of degree 44 that is not algebraic. The construction relies on the geometry of bielliptic surfaces of type 2.

Keywords

Cite

@article{arxiv.2602.13435,
  title  = {A surface with representable $\text{CH}_{0}$-group but no universal zero-cycle},
  author = {Theodosis Alexandrou},
  journal= {arXiv preprint arXiv:2602.13435},
  year   = {2026}
}

Comments

30 pages, minor revisions; several assumptions have been relaxed, examples have been added and the exposition has been improved

R2 v1 2026-07-01T10:36:13.189Z