Vectorlike leptons and long-lived bosons at the LHC

Abstract

We study a renormalizable theory that includes a heavy weak-singlet vectorlike lepton, ${\tau }^{\prime }$, that decays into a pseudoscalar boson and a tau lepton. We show that this can be the dominant decay mode of ${\tau }^{\prime }$ provided the pseudoscalar couplings deviate from the case of a Nambu-Goldstone boson. For a range of parameters, the pseudoscalar is long-lived, and mainly decays into a photon pair at one loop, or into a tau pair at tree level. Electroweak production of ${\tau }^{\prime +}{\tau }^{\prime -}$ leads to a rich phenomenology at colliders, including signals with many taus or photons. We analyze in detail the LHC signal involving two prompt taus and two displaced photon pairs. Particularly interesting is the case where the pseudoscalar has a decay length of a few meters and thus would typically deposit energy in the muon chambers of the CMS or ATLAS detectors.

arXiv comment30 pages, 9 figures; v2: includes NLO cross sections in Figure 3, presentation improvements, more references, matches published version

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Cited by in corpus (6)

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• Interplay of inert doublet and vector-like lepton triplet with displaced vertices at the LHC/FCC and MATHUSLA
• The Two Scales of New Physics in Higgs Couplings
• Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Mutually elusive: vectorlike antileptons and leptoquarks
• Multi-top signals of vectorlike quarks at the LHC