Probing TeV-scale Majorana neutrinos at a muon-proton collider via a lepton-number-violating fat-jet signature

Abstract

We investigate the sensitivity to TeV-scale heavy Majorana neutrinos at a future muon-proton collider with

 TeV, based on 1 TeV muon and 7 TeV proton beams. We focus on the lepton-number-violating (LNV) process

$$\mu ^- p \rightarrow jN$$ μ - p → j N

, followed by

$$N\rightarrow \mu ^+W^-\rightarrow \mu ^+J$$ N → μ + W - → μ + J

, leading to the characteristic final state

$$j\mu ^+J$$ j μ + J

. Here, j denotes the associated light jet from heavy-neutrino production, while J denotes the fat jet originating from the hadronic d ecay of the highly boosted W boson. This topology provides a clean experimental signature with strongly suppressed Standard Model backgrounds. A comprehensive signal and background analysis is performed using parton showering, fast detector simulation, and dedicated fat-jet reconstruction. We derive the projected

$$2\sigma $$ 2 σ

exclusion limits on the muon-flavor mixing parameter

$$|V_{\mu N}|^2$$ | V μ N | 2

for integrated luminosities of 100 fb

$$^{-1}$$ - 1

and 1 ab

$$^{-1}$$ - 1

. For heavy-neutrino masses in the range

$$1~\textrm{TeV}\le m_N\le 3~\textrm{TeV}$$ 1 TeV ≤ m N ≤ 3 TeV

, the projected upper limits on

$$|V_{\mu N}|^2$$ | V μ N | 2

range from

$$2.6\times 10^{-6}$$ 2.6 × 10 - 6

to

$$5.9\times 10^{-5}$$ 5.9 × 10 - 5

at 1 ab

$$^{-1}$$ - 1

. These results show that a future

$$\mu p$$ μ p

collider can provide competitive and complementary sensitivity to TeV-scale heavy Majorana neutrinos compared with other proposed high-energy facilities.