BPS Conditions of Supermembrane on the PP-wave
  We study the BPS conditions in the closed supermembranes on the maximally supersymmetric pp-wave background. In particular, the 1/2 and 1/4 BPS states are discussed in detail. Moreover, we comment on the zero-modes in the invariant mass formulae of the theory. 
Katsuyuki Sugiyama and Kentaroh Yoshida (Kyoto Univ.)