Superheavy-quarkonium decays with two Higgs doublets

We study the decay modes of a S-wave superheavy quarkonium, formed by a possible fourth-generation quark in two-Higgs-doublet models. Because of the enhancement of Yukawa couplings and longitudinal weak bosons the main decays of these superheavy states will be into neutral scalar bosons Hi0Hj0 and a charged scalar plus a W boson. If the HW± channel is open for the (1 - ) superheavy quarkonium it will provide a quite clean signal for a charged Higgs boson. The decay of the pseudoscalar quarkonium (0-+) into a Z boson and one of the scalars will also be present in a large amount. © 1989 The American Physical Society.