Testing neutrino dipole portal by long-lived particle detectors at the LHC

We discuss the potential of using detectors aimed for searching long-lived particles (LLP) at the high-luminosity LHC run, to probe the neutrino dipole models. This is achieved by taking the heavy neutral leptons (HNL) of the models as candidates of the LLPs. Taking into account the dipole couplings to the weak bosons, d_W,Z , which control the production of the HNLs at the LHC, we discuss the reach on the electromagnetic dipole couplings, d_γ , by searching for a single high-energy photon at LLP detectors. Four typical scenarios are considered in this paper, scenario A, B with d_W=0 or d_Z=0 , and scenario C, D with d_W,Z≫ d_γ . We show the sensitivity on d_γ , can be fairly different depending on the relations between the d_W,Z and d_γ . And the LLP detectors can potentially extend the sensitivity on dipole couplings during the high-luminosity runs of the LHC in certain scenarios.