Origin of Soft Limits from Nonlinear Supersymmetry in Volkov-Akulov   Theory
  We apply the background field technique, recently developed for a general class of nonlinear symmetries, at tree level, to the Volkov-Akulov theory with spontaneously broken N=1 supersymmetry. We find that the background field expansion in terms of the free fields to the lowest order reproduces the nonlinear supersymmetry transformation rules. The double soft limit of the background field is, in agreement with the new general identities, defined by the algebra of the nonlinear symmetries. 
Renata Kallosh, Anna Karlsson, Divyanshu Murli
hep-th