Quasi-Dirac neutrinos in the linear seesaw model

We implement a minimal linear seesaw model (LSM) for addressing the Quasi-Dirac (QD) behaviour of heavy neutrinos, focusing on the mass regime of MN . MW . Here we show that for
relatively low neutrino masses, covering the few GeV range, the same-sign to opposite-sign dilepton ratio, R`` , can be anywhere between 0 and 1, thus signaling a Quasi-Dirac regime. Particular
values of R`` are controlled by the width of the QD neutrino and its mass splitting, the latter
being equal to the light-neutrino mass mν in the LSM scenario. The current upper bound on mν1
together with the projected sensitivities of current and future |UN` |
2
experimental measurements,
set stringent constraints on our low-scale QD mass regime. Some experimental prospects of testing
the model by LHC displaced vertex searches are also discussed.