Hyper-K\"ahler quotients of solvable Lie groups
  In this paper we apply the hyper-K\"ahler quotient construction to Lie groups with a left invariant hyper-K\"ahler structure under the action of a closed abelian subgroup by left multiplication. This is motivated by the fact that some known hyper-K\"ahler metrics can be recovered in this way by considering different Lie group structures on $\H^p \times \H^q$ ($\H$: the quaternions). We obtain new complete hyper-K\"ahler metrics on Euclidean spaces and give their local expressions. 
M. L. Barberis, I. Dotti, A. Fino