Pseudoscalar Higgs bosons at the LHC: production and decays into electroweak gauge bosons revisited

We analyse and compute, within a number of standard model (SM) extensions, the cross sections sigma (A -> VV') for the production of a heavy neutral pseudoscalar Higgs-boson/spin-zero resonance at the LHC and its subsequent decays into electroweak gauge bosons. For comparison we calculate also the corresponding cross sections for a heavy scalar. The SM extensions we consider include a type-II two-Higgs doublet model (2HDM), a 2HDM with four chiral fermion generations, the minimal supersymmetric extension of the SM (MSSM), and top-colour assisted technicolour models. Presently available phenomenological constraints on the parameters of these models are taken into account. We find that, with the exception of the MSSM, these models permit the LHC cross sections sigma (A -> VV') to be of observable size. That is, a pseudoscalar resonance may be observable, if it exists, at the LHC in its decays into electroweak gauge bosons, in particular in WW and gamma gamma final states.