Nonlinear (4,8,4) multiplet of N=8, d=1 supersymmetry

We construct a nonlinear version of the d = 1 off-shell N = 8 multiplet (4, 8, 4), proceeding from a nonlinear realization of the superconformal group OSp(4*vertical bar 4) in the N = 8, d = 1 analytic bi-harmonic superspace. The new multiplet is described by a double-charged analytic Goldstone superfield q(1,1) subjected to some nonlinear OSp(4*vertical bar 4) covariant harmonic constraints. We construct the most general N = 8 supersymmetric actions of q(1,1) and find the general expression for the bosonic target metric in terms of the original analytic Lagrangian superfield density which is thus the target geometry prepotential. It also completely specifies the scalar potential. The metric is conformally flat and, in the SO(4) invariant case, is a deformation of the metric of S-4. (c) 2006 Elsevier B.V. All rights reserved.