Journal Club

Seminar Room

If you want to propose a paper, you can contact Supratim Das Bakshi (sdb AT

Tuesday 15th of March, 2022

The ALPs from the Top: Searching for long lived axion-like particles from exotic top decays

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 $t\bar{t}$ 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.
Comments: 16 pages, 7 figures, 2 tables
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: MITP/22-017
Cite as: arXiv:2202.09371 [hep-ph]
  (or arXiv:2202.09371v1 [hep-ph] for this version)

Submission history

From: Adrian Carmona [view email
[v1] Fri, 18 Feb 2022 19:00:01 UTC (4,728 KB)

Presented by Adrián

Also, José María will talk on his work on Little Higgs models.