On a characterization of unbounded homogeneous domains with boundaries   of light cone type
  We determine the automorphism groups of unbounded homogeneous domains with boundaries of light cone type. Furthermore we present the group-theoretic characterization of the domain. As a corollary we prove the non-existence of compact quotients of a unbounded homogeneous domain. We also give a counterexample of the characterization. 
Jun-ichi Mukuno, Yoshikazu Nagata
math.CV