Solutions of D_\alpha - 0 from Homogeneous Invariant Functions
  We prove that the existence of a homogeneous invariant of degree n for a representation of a semi-simple Lie group guarantees the existence of non-trivial solutions of D_{\alpha} = 0: these correspond to the maximum value of the square of the invariant divided by the norm of the representation to the n^{th} power. 
F. Buccella