CP Violation in Supersymmetric Theories: stop2 -> stop1 tau- tau+
  Supersymmetric (SUSY) theories include many new parameters, some of which are CP-violating. Assuming that SUSY is found at a future high-energy collider, we examine the decay stop2 -> stop1 tau- tau+ with an eye to obtaining information about the new CP phases. We show that there are two CP-violating asymmetries which can be large in some regions of the SUSY parameter space. These involve measuring one or both of the tau spins. These asymmetries are particularly sensitive to phi_At, the phase of the trilinear coupling A_t. 
Ken Kiers, Alejandro Szynkman and David London