Worldsheet Supersymmetry of Pohlmeyer-Reduced AdS_n x S^n Superstrings
  As was observed by Grigoriev and Tseytlin, the Pohlmeyer-reduced AdS_2 x S^2 superstring theory possesses N=(2,2) worldsheet supersymmetry. We show, at the classical level, that the AdS_3 x S^3 and AdS_5 x S^5 superstring theories in the Pohlmeyer-reduced form reveal hidden N=(4,4) and N=(8,8) worldsheet supersymmetries. Our consideration is based on the modified mass-deformed gauged WZW action for the superstring equations. We present the explicit form of the supersymmetry transformations for both the off-shell action and the superstring equations. The characteristic feature of these transformations is the presence of non-local terms. 
M. Goykhman, E. Ivanov
hep-th math-ph math.MP