The field of invariants for the adjoint action of the Borel group in the   nilradical of a parabolic subalgebra
  In this paper the field of invariants for the adjoint action of the Borel group in the nilradical of a parabolic subalgebra is studied. We construct the set of B-invariant rational functions generating the field of invariants. 
Victoria Sevostyanova
math.RT