The ALPs from the top: searching for long lived axion-like particles from exotic top decays
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AuthorCarmona Bermúdez, Adrián
Axions and ALPsNew Light ParticlesTop FCNC
Carmona, A... [et al.]. The ALPs from the top: searching for long lived axion-like particles from exotic top decays. J. High Energ. Phys. 2022, 122 (2022). [https://doi.org/10.1007/JHEP07(2022)122]
SponsorshipEuropean Commission 754446; UGR Research and Knowledge Transfer Found-Athenea3i; Spanish Government PID2019-106087GB-C22; Junta de Andalucia A-FQM-472UGR20; German Research Foundation (DFG) PRISMA+ EXC 2118/1 39083149; Federal Ministry of Education & Research (BMBF) 05H18UMCA1
We propose a search for long lived axion-like particles (ALPs) in exotic top decays. Flavour-violating ALPs appear as low energy effective theories for various new physics scenarios such as t-channel dark sectors or Froggatt-Nielsen models. In this case the top quark may decay to an ALP and an up- or charm-quark. For masses in the few GeV range, the ALP is long lived across most of the viable parameter space, suggesting a dedicated search. We propose to search for these long lived ALPs in t¯t events, using one top quark as a trigger. We focus on ALPs decaying in the hadronic calorimeter, and show that the ratio of energy deposits in the electromagnetic and hadronic calorimeters as well as track vetoes can efficiently suppress Standard Model backgrounds. Our proposed search can probe exotic top branching ratios smaller than 10−4 with a conservative strategy at the upcoming LHC run, and potentially below the 10−7 level with more advanced methods. Finally we also show that measurements of single top production probe these branching ratios in the very short and very long lifetime limit at the 10−3 level.