Mass limits of invisibly decaying Higgs particles from the CERN LEP data

In the Majoron models the SU(2) Higgs doublet can decay invisibly into a Majoron pair via its mixing with a singlet. An analysis of the CERN LEP data shows the invisible decay mode to be more visible than the SM decay. For these models, the dominantly doublet Higgs field $H$ is shown to have a mass limit within ±6 GeV of the SM limit irrespective of the model parameters. But the dominantly singlet one $S$ can be arbitrarily light for a sufficiently small mixing angle.