Nested disappearing-track plus displaced-vertex topology at the HL-LHC: a dual long-lived-particle signature of the scotogenic model
Year: 2026
Type: article
Abstract: The scotogenic model generates sub-eV neutrino masses radiatively through small Yukawa couplings $$\sim \mathcal {O}(10^{-3})$$ ∼ O ( 10 - 3 ) that also set the decay length of the heavy neutral fermion $$N_2$$ N 2 ; in the compressed regime a separate, much smaller Yukawa entry $$\sim \mathcal {O}(10^{-6})$$ ∼ O ( 10 - 6 ) additionally renders the charged scalar $$\tilde{\eta }^{\pm }$$ η ~ ± long-lived. We study the compressed-spectrum regime of its two-inert-doublet variant ( $$\varDelta M_{\textrm{comp}}= m_{\tilde{\eta }^\pm }- m_{N_2}\simeq 200\,\text {MeV}$$ Δ M comp = m η ~ ± - m N 2 ≃ 200 MeV ), in which small Yukawa entries render both the charged scalar $$\tilde{\eta }^{\pm }$$ η ~ ± and the heavy neutral fermion $$N_2$$ N 2 long-lived and produce a nested cascade at the High-Luminosity LHC (HL-LHC): $$\tilde{\eta }^{\pm }$$ η ~ ± leaves a disappearing track (DT), decays to an invisible $$N_2$$ N 2 , which travels macroscopically before forming a displaced dilepton vertex (DV). The two slow flights combine into a 4D time-of-flight delay $$\varDelta t\sim 200$$ Δ t ∼ 200 – $$800\,\text {ps}$$ 800 ps 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 $$B\sim 10^{-5}$$
Source: The European Physical Journal C
Author: Renjie Wang
Institution: Institute of High Energy Physics
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7214150815