Triple Pseudoscalar Decay Mode, $Z \to AAA$
  We analyze the production of triple pseudoscalar Higgs bosons in the decay channel of $Z\rightarrow AAA$ for light pseudoscalar bosons when the corresponding scalar boson is too heavy to be produced by $Z$ decay. Analytic results are obtained both at the tree level and at the one--loop level. The branching fraction can be as large as $10^{-5}$ which should be detectable at LEP. 
Darwin Chang and W.-Y. Keung