Variations on a Higgs theme

Abstract

We show how the $Z$ boson can be generated in gluon-gluon fusion and yield two photons, via $gg\to Z\to \gamma \gamma$, through massive fermion loops only, thereby contributing events to a candidate Higgs sample in the di-photon channel. A sub-leading contribution also exists from $q\bar{q}\to Z\to \gamma \gamma$ events. Assuming the Standard Model, the corresponding event rates are negligible at the LHC stages of 7, 8 TeV, given the luminosities collected therein (about 5 and 20 fb${}^{-1}$, respectively). Conversely, at 14 TeV, the first process become accessible for luminosities of order 300 fb${}^{-1}$. Finally, we show how additional fermion states entering such loops, in production, in decay or in both cases, could affect the predictions in this channel by curiously mimicking Higgs signals.

18 pages, 1 table, 4 figures

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