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, $d_\gamma$, 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 $d_{W,Z}\gg d_\gamma$. We show the sensitivity on $d_\gamma$, can be fairly different depending on the relations between the $d_{W,Z}$ and $d_\gamma$. And the LLP detectors can potentially extend the sensitivity on dipole couplings during the High-luminosity runs of the LHC in certain scenarios.