Discrimination of models including H ^±± by using tau decay

The doubly charged scalar boson (H^±±) is introduced in several models of the new physics beyond the standard model. The H^±± can have Yukawa interactions with two left-handed charged leptons or two righthanded charged leptons. We study kinematical properties of H^±± decay products through tau leptons in order to discriminate the chiral structures of the new Yukawa interaction. The chirality of tau leptons can be measured by the energy distributions of the tau decay products, and thus the chiral structure of the new Yukawa interaction can be traced in the invariant-mass distributions of the H ^±± decay products [1].