Multi-Higgs doublet model: Can it account for ℓ+ℓ−γγ events?
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Motivated by recent experiments at LEP (Z →ℓ+ ℓ− γγ, withMγγ-59 GeV), we examine the possibility that such events are explained by a Bjorken process with a resonant Higgs (Mho ≏59 GeV) decaying to γγ. We investigate theN-doublet-Higgs model withoutCP violation. Under the simplifying assumption that(N-k) doublets (k≥ 1) decouple from the fermion sector, we could only explain the observed events if: i)(N- 1) ≥ 2 and ii) the masses of the corresponding(N- 1) neutral scalars are either completely or almost degenerate,i.e. the decay Z →ℓ+ℓ− γγ proceeds now via several overlapping resonances. Such a scenario would require fine tuning. Furthermore, the deficit of the observed decays Z → → vvγ, qqγγ (atMγγ∽59 GeV) indicates that one either has to go beyond simple extensions of the minimal standard model, or one has to wait for more experimental data.
PACS 12.90Miscellaneous theoretical ideas and models
PACS 12.15.JiApplications of electroweak models to specific processes
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