D. Arnal et al., INTERTWINING-OPERATORS FOR EXPONENTIAL LI E-GROUPS, Comptes rendus de l'Academie des sciences. Serie 1, Mathematique, 319(6), 1994, pp. 549-551
Let G be an exponential Lie group with Lie algebra g. Let f be in the
dual g of g. If h1 and h2 are two polarizations at f which satisfy Pu
kansky's condition, then the representations pi(i) = ind(Hi)G chi(f) [
i = 1, 2, H(i) = exp h(i), chi(f) (exp X) = e(if)(X) for X in g], are
irreducible and equivalent. The main problem for constructing an inter
twining operator is to prove the convergence of a certain integral. In
this Note we present an explicit intertwining operator for pi1 and pi
2 which avoids this difficulty.