Let $M$ be a symplectic manifold (not Kaehler). Does there exists in a neighbourhood of the zero section in the cotangent bundle $T^{*}M$ a Hyperkaehler structure? I know that by the paper by Feix on can construct such structures if $M$ is Kaehler. Does this also hold or is there a similar construction in the waker case the symplectic case?
Greetings mirta