Verma modules for Yangians
  We study the Verma modules M(mu(u)) over the Yangian Y(a) associated with a simple Lie algebra a. We give necessary and sufficient conditions for irreducibility of M(mu(u)). Moreover, regarding the simple quotient L(mu(u)) of M(mu(u)) as an a-module, we give necessary and sufficient conditions for finite-dimensionality of the weight subspaces of L(mu(u)). 
Y. Billig, V. Futorny and A. Molev