Nested Disappearing-Track plus Displaced-Vertex Topology at the HL-LHC: A Dual Long-Lived-Particle Signature of the Scotogenic Model
Abstract
The scotogenic model generates sub-eV neutrino masses radiatively through small Yukawa couplings ∼𝒪(10−3) that also set the decay length of the heavy neutral fermion Ntwo; in the compressed regime a separate, much smaller Yukawa entry ∼𝒪(10−6) additionally renders the charged scalar etapm long-lived. We study the compressed-spectrum regime of its two-inert-doublet variant (DMcomp = mHpm − mNtwo ≃ 200MeV), in which small Yukawa entries render both the charged scalar etapm and the heavy neutral fermion Ntwo long-lived and produce a nested cascade at the High-Luminosity LHC~(HL-LHC): etapm leaves a disappearing track~(DT), decays to an invisible Ntwo, which travels macroscopically before forming a displaced dilepton vertex~(DV). The two slow flights combine into a 4D time-of-flight delay dt∼200--800ps resolvable by the CMS MIP Timing Detector, while the DT-to-DV displacement vector inherits the parent track direction, yielding a spatial back-pointing correlation with no SM analogue. These two handles are expected to suppress the background to B∼10−5--10−3 events, and the discovery remains 5σ-significant for any background up to B∼10 events. At the benchmark (mNtwo=150GeV and proper decay lengths ctauH=300mm, ctauN=189mm) the strategy yields Ns≈1212 signal events at 3000ifb and establishes sensitivity across 15mm≲ctauH≲300mm, 10mm≲ctauN≲1000mm, a correlated region left uncovered by any standalone DT or DV search. Because the Ntwo decay length is controlled by the same Yukawa couplings that generate sub-eV neutrino masses, mapping this nested cascade turns the HL-LHC into a direct collider probe of the interaction responsible for neutrino mass.
Versions
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BibTeX
@misc{wang2026nested,
title = {{Nested Disappearing-Track plus Displaced-Vertex Topology at the HL-LHC: A Dual Long-Lived-Particle Signature of the Scotogenic Model}},
author = {Renjie Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28334},
eprint = {2609.28334},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28334},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Nested Disappearing-Track plus Displaced-Vertex Topology at the HL-LHC: A Dual Long-Lived-Particle Signature of the Scotogenic Model
AU - Renjie Wang
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28334
UR - https://arxiv.org/abs/2609.28334
AB - The scotogenic model generates sub-eV neutrino masses radiatively through small Yukawa couplings ∼𝒪(10^−3) that also set the decay length of the heavy neutral fermion Ntwo; in the compressed regime a separate, much smaller Yukawa entry ∼𝒪(10^−6) additionally renders the charged scalar etapm long-lived. We study the compressed-spectrum regime of its two-inert-doublet variant (DMcomp = mHpm − mNtwo ≃ 200MeV), in which small Yukawa entries render both the charged scalar etapm and the heavy neutral fermion Ntwo long-lived and produce a nested cascade at the High-Luminosity LHC~(HL-LHC): etapm leaves a disappearing track~(DT), decays to an invisible Ntwo, which travels macroscopically before forming a displaced dilepton vertex~(DV). The two slow flights combine into a 4D time-of-flight delay dt∼200--800ps resolvable by the CMS MIP Timing Detector, while the DT-to-DV displacement vector inherits the parent track direction, yielding a spatial back-pointing correlation with no SM analogue. These two handles are expected to suppress the background to B∼10^−5--10^−3 events, and the discovery remains 5σ-significant for any background up to B∼10 events. At the benchmark (mNtwo=150GeV and proper decay lengths ctauH=300mm, ctauN=189mm) the strategy yields N_s≈1212 signal events at 3000ifb and establishes sensitivity across 15mm≲ctauH≲300mm, 10mm≲ctauN≲1000mm, a correlated region left uncovered by any standalone DT or DV search. Because the Ntwo decay length is controlled by the same Yukawa couplings that generate sub-eV neutrino masses, mapping this nested cascade turns the HL-LHC into a direct collider probe of the interaction responsible for neutrino mass.
ER -