On the KP I transonic limit of two-dimensional Gross-Pitaevskii   travelling waves
  We provide a rigorous mathematical derivation of the convergence in the long-wave transonic limit of the minimizing travelling waves for the two-dimensional Gross-Pitaevskii equation towards ground states for the Kadomtsev-Petviashvili equation (KP I). 
Fabrice B\'ethuel (LJLL), Philippe Gravejat (CEREMADE), Jean-Claude   Saut (LM-Orsay)