Displaced vertices as probes of sterile neutrino mixing at the LHC

Abstract: We investigate the reach at the LHC to probe light sterile neutrinos with displaced vertices. We focus on sterile neutrinos $N$ with masses $m_{N} \sim $ (5-30) GeV, that are produced in rare decays of the Standard Model gauge bosons and decay inside the inner trackers of the LHC detectors. With a strategy that triggers on the prompt lepton accompanying the $N$ displaced vertex and considers charged tracks associated to it, we show that the 13 TeV LHC with $3000$/fb is able to probe active-sterile neutrino mixings down to $|V_{lN}|^2\approx 10^{-9}$, with $l=e,\mu$, which is an improvement of up to four orders of magnitude when comparing with current experimental limits from trileptons and proposed lepton-jets searches. In the case when $\tau$ mixing is present, mixing angles as low as $|V_{\tau N}|^2 \approx 10^{-8}$ can be accessed.