| Résume||ZOOM 811 7744 0900, pas de mot de passe mais salle d'attente.
Abstract: Maulik and Pandharipande proved a relation between three different theories associated to a 1-parameter family of smooth K3 surfaces:
(i) the Gromov-Witten invariants of the total space of the family in fiber classes
(ii) the Noether-Lefschetz numbers of the family
(iii) the (reduced) Gromov-Witten invariants of a fiber.
A similar version holds for any family of holomorphic-symplectic varieties. In this talk I will explain what shape this relation takes for K3-type, and what it implies for Noether-Lefschetz numbers of Debarre-Voisin fourfolds. In particular, this leads to a new proof (and strengthening) of a result of Debarre, Han, O’Grady and Voisin on the existence of HLS divisors on the moduli of DV fourfolds.|