On Hyper K\"ahler manifolds associated to Lagrangean K\"ahler submanifolds of $T^*{\Bbb C}^n$

Abstract

For any Lagrangean K\"ahler submanifold $M \subset T^*{\Bbb C}^n$, there exists a canonical hyper K\"ahler metric on $T^*M$. A K\"ahler potential for this metric is given by the generalized Calabi Ansatz of the theoretical physicists Cecotti, Ferrara and Girardello. This correspondence provides a method for the construction of (pseudo) hyper K\"ahler manifolds with large automorphism group. Using it, a class of pseudo hyper K\"ahler manifolds of complex signature $(2,2n)$ is constructed. For any hyper K\"ahler manifold $N$ in this class a group of automorphisms with a codimension one orbit on $N$ is specified. Finally, it is shown that the bundle of intermediate Jacobians over the moduli space of gauged Calabi Yau 3-folds admits a natural pseudo hyper K\"ahler metric of complex signature $(2,2n)$.