Exploring Scalar Leptoquarks at Muon Collider via Indirect Signatures and Right-Handed Neutrino-Assisted Decays

Abstract: We explore the discovery prospects of the scalar leptoquark doublet $\widetilde{R}_{2}({3},{2},1/6)$ at a future high-energy muon collider, considering both direct and indirect search strategies. For indirect search, we probe the relevant Yukawa couplings by analyzing the dijet final state via virtual exchange of the leptoquark. Even with a sub-$\mathcal{O}(1)$ Yukawa coupling, we achieve a 5$\sigma$ sensitivity up to leptoquark mass $ \sim 4$ TeV ($7$ TeV) at $\sqrt{s}=5, (10)$ TeV center-of-mass energy with $\mathcal{L} = 3 {ab}^{-1}$ ($10 ab^{-1}$) integrated luminosity. For direct search, we consider the pair and single production of leptoquarks and their subsequent decay to a right-handed neutrino and a light jet. Direct searches simultaneously target leptoquarks and right-handed neutrinos across four production modes--Pair/Single Symmetric and Pair/Single Asymmetric--enabled by Yukawa coupling-driven decays. A unified and minimal selection strategy requiring two muons and at least four jets proves effective across all modes and for leptoquark masses in a wide range. We demonstrate that with $\mathcal{O}(1)$ Yukawa couplings, the single production channel can probe leptoquark masses up to 3 TeV (6 TeV) for $\sqrt s=5$ TeV (10 TeV). Our results highlight the superior sensitivity of muon collider over HL-LHC and the power of a simplified, benchmark-independent search strategy in accessing TeV-scale new physics.