HyperK\"ahler Potentials via Finite-Dimensional Quotients

It is known that nilpotent orbits in a complex simple Lie algebra admit hyperK\"ahler metrics with a single function that is a global potential for each of the K\"ahler structures (a hyperK\"ahler potential). In an earlier paper the authors showed that nilpotent orbits in classical Lie algebras can be constructed as finite-dimensional hyperK\"ahler quotient of a flat vector space. This paper uses that quotient construction to compute hyperK\"ahler potentials explicitly for orbits of elements with small Jordan blocks. It is seen that the K\"ahler potentials of Biquard and Gauduchon for SL(n)-orbits of elements with X^2=0, are in fact hyperK\"ahler potentials.