Fat Jet Signature of a Heavy Neutrino at Lepton Collider

Abstract

We explore the discovery prospect of a very heavy neutrino at the proposed $e^{+}{e}^{-}$ collider for two different c.m.energies $\sqrt{s}=1.4$ TeV and 3 TeV. We consider production of heavy neutrino via $s$ and $t$-channel processes, and its subsequent prompt decays leading to semi-leptonic final states, along with significant missing energy. For our choice of masses, the gauge boson produced from heavy neutrino decay is highly boosted, leading to a fat-jet. We carry out a detail signal and background analysis for $e^{\pm }+j_{\mathrm{fat}}+{\cancel{E}}_T$ final state using both cut based and multivariate techniques. We show that a heavy neutrino of mass $600-2700$ GeV and active-sterile mixing $|V_{eN}{|}^2\sim 10^{-5}$ can be probed with $5\sigma$ significance at $e^{+}{e}^{-}$ collider after collecting $\mathcal{L}=500$ ${\mathrm{fb}}^{-1}$ of data. We find the sensitivity reach at $e^{+}{e}^{-}$ collider is order of magnitude enhanced as compared to LHC.

Comments: 25 pages, 13 figures and 6 tables