Kobayashi pseudometric on hyperkahler manifolds

Ljudmila Kamenova, Steven Lu, Misha Verbitsky

Published 2013-08-26, updated 2013-09-26Version 2

The Kobayashi pseudometric on a complex manifold $M$ is the maximal pseudometric such that any holomorphic map from the Poincare disk to $M$ is distance-decreasing. Kobayashi has conjectured that this pseudometric vanishes on Calabi-Yau manifolds. Using ergodicity of complex structures, we prove this result for any hyperkaehler manifold if it admits a deformation with a Lagrangian fibration, and its Picard rank is not maximal. The SYZ conjecture claims that any parabolic nef line bundle on a deformation of a given hyperkaehler manifold is semi-ample. We prove that the Kobayashi pseudometric vanishes for all hyperkaehler manifolds satisfying the SYZ property. This proves the Kobayashi conjecture for K3 surfaces and their Hilbert schemes.