Nonperturbative Effects in Event Shapes from Soft-Collinear Effective   Theory
  Soft-collinear effective theory (SCET) is used to demonstrate factorization for event shape distributions in the two-jet region. The leading nonperturbative power corrections to these distributions can be characterized as shape functions defined in terms of Wilson lines of soft gluons. The relation of these results to the well-known predictions for shifts in the distributions induced by the leading power corrections is discussed. 
Christopher Lee