Determination of the CP parity of Higgs bosons in their tau decay   channels at the ILC
  We investigate a method for determining the CP nature of a neutral Higgs boson or spin-zero resonance at a future linear e+e- collider (ILC) in its tau decay channel. Our procedure is applicable if the production vertex of the Higgs boson can be measured. This will be the case, for example, for the Higgs-strahlung process. We show that the method is feasible for both the leptonic and the hadronic 1-prong tau decay modes. 
Stefan Berge, Werner Bernreuther, Hubert Spiesberger
hep-ph hep-ex