Displaced fat-jets and tracks to probe boosted right-handed neutrinos in the U(1)_{B-L} model

Abstract

We investigate the pair-production of Right-Handed Neutrinos (RHNs) via a B-LZ' boson and present the sensitivity studies of the active-sterile neutrino mixing (|V_{mu N}|) at the High-Luminosity run of the LHC (HL-LHC) and a future pp collider (FCC-hh). We focus on RHN states with a mass of 10-70 GeV which naturally results in displaced vertices for small |V_{mu N}|. Being produced through a mass resonance with M_{Z'} ge 1 TeV, the RHNs are heavily boosted, leading to collimated decay products that give rise to fat-jets. We investigate the detection prospect of dedicated signatures in the inner detector and the muon spectrometer, namely a pair of displaced fat-jets and the associated tracks, respectively. We find that both the HL-LHC and FCC-hh can be sensitive to |V_{mu N}| > 10^{-6} and |V_{mu N}| > 10^{-7} with the number of events reaching {mathcal {O}}(10) and {mathcal {O}}(10^3), respectively. This allows probing the generation of light neutrino masses through the Seesaw mechanism.