Searches for heavy neutrinos at a 3 TeV CLIC in fat jet final states

TL;DR

This study investigates the potential of a 3 TeV CLIC to detect heavy Majorana neutrinos through fat jet final states, providing detailed sensitivity projections and comparing with existing constraints.

Contribution

It introduces new search strategies for TeV-scale heavy neutrinos at CLIC, including detailed detector simulations and background analysis for fat jet signatures.

Findings

CLIC can improve sensitivity to heavy neutrino mixing by two orders of magnitude.

The study establishes exclusion and discovery limits in the heavy neutrino mass and mixing parameter space.

Results show competitive sensitivity compared to future hadron colliders and other CLIC channels.

Abstract

Heavy Majorana neutrinos ($N$) are predicted in many models of physics beyond the Standard Model. In this work, we explore the production and detection prospects of TeV-scale heavy neutrinos ($m_N \gtrsim 1$ TeV) at a future 3 TeV Compact Linear Collider (CLIC). We focus on two distinct decay topologies: (i) $N \to \ell^{\pm} W^{\mp}$ with hadronic $W$ boson decay, leading to a final state with one charged lepton and a hadronic fat-jet $J_W$; and (ii) $N \to \nu h$ with subsequent Higgs decay $h \to b\bar{b}$, yielding a Higgs-tagged fat-jet $J_h$ and $\slashed{E}_T$. Based on comprehensive detector-level simulations and background analysis, we present both $2\sigma$ exclusion limits and $5\sigma$ discovery reaches in the $m_N$-$|V_{\ell N}|^2$ plane. We further extract 95\% confidence level upper limits on the mixing parameter $|V_{\ell N}|^2$, and perform a detailed comparison with existing constraints from direct searches at future colliders and indirect global fits. Our findings demonstrate that a 3 TeV CLIC can improve the sensitivity to $|V_{\ell N}|^2$ by about two orders of magnitude compared to the projected reaches of future hadron colliders, while remaining competitive with other CLIC search channels.