Non-Relativistic Superstrings: A New Soluble Sector of AdS_5xS^5
  We find a new sector of string theory in AdS_5xS^5 describing non-relativistic superstrings in that geometry. The worldsheet theory of non-relativistic strings in AdS_5xS^5 is derived and shown to reduce to a supersymmetric free field theory in AdS_2. Non-relativistic string theory provides a new calculable setting in which to study holography. 
Jaume Gomis, Joaquim Gomis and Kiyoshi Kamimura