MSSM Higgs sector CP violation at photon colliders: Revisited
  We present a comprehensive analysis on the MSSM Higgs sector CP violation at photon colliders including the chargino contributions as well as the contributions of other charged particles. The chargino loop contributions can be important for the would-be CP odd Higgs production at photon colliders. Polarization asymmetries are indispensable in determining the CP properties of neutral Higgs bosons. 
Saebyok Bae, Byungchul Chung and P. Ko