Les Houches

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Responsible: Jose Miguel No

Participants: …

The starting point is the review/compendium work on exotic Higgs decays from Curtin, Gori, Shelton, Strassler… 1312.4992, which delineates a programme to cover as many exotic decays of the 125 GeV Higgs (and provide motivation!) as possible. While the list of possible decays in the review is quite exhaustive, several of these decays have not been studied in detail. Two such cases are h → Z a (with a pseudoscalar a that decays visibly, eg. into gammagamma) and semi-visible decays like h→ gamma + E_T^miss, h→ gamma gamma + E_T^miss, h→ Z + E_T^miss (e.g. h → Z a with a → E_T^miss).

Visible decays: search for axion-like particles (ALPs) via h → Z a (a → gamma gamma). Preliminary study from Bauer, Neubert, Thamm 1708.00443. They put limits on very light ALPs (m_a < 47 MeV) from constraints on h → Z gamma, since for m_a < 47 MeV the two photons from the ALP decay are very collimated and seen as one in the detector. For not-so-light ALPs, they compute just number of signal events.

Goal would be to provide a better estimate of LHC sensitivity to h → Z a, a → gamma gamma resolved (including some sort of background study?).

Semi-visible decays: