Eur. Phys. J. C (2025) 85: 718
https://doi.org/10.1140/epjc/s10052-025-14400-w

Regular Article - Theoretical Physics

Searching for heavy majorana neutrinos at the FCC-eh via lepton-number-violating and fat-jet final states

School of Biomedical Engineering, Xinxiang Medical University, 453003, Xinxiang, China

^a shjf@xxmu.edu.cn

Received: 26 March 2025
Accepted: 1 June 2025
Published online: 30 June 2025

Abstract

Within the framework of the phenomenological type-I seesaw mechanism, heavy singlet Majorana neutrinos are introduced to explain the origin of neutrino masses. We propose a novel search strategy for these heavy Majorana neutrinos through the lepton-number-violating process $e^{-}p\to jN\to j({\mu }^{+}{W}^{-})$ at the Future Circular electron-hadron Collider (FCC-eh), which would utilize a 60 GeV electron beam colliding with a 50 TeV proton beam. Focusing on the decay mode $N\to {\mu }^{+}{W}^{-}\to {\mu }^{+}J$, where J denotes a fat-jet from the hadronic decays of a highly boosted W boson, we investigate the discovery potential of this signature. By performing a detailed signal-to-background analysis and detector simulations, we present $2\sigma$ exclusion limits and $5\sigma$ discovery reaches in terms of parameter space regions.