Probing $\Delta L=2$ lepton number violating SMEFT operators at the same-sign muon collider

TL;DR

This paper explores how same-sign muon colliders can detect lepton number violation caused by specific SMEFT operators, offering a new method to probe physics beyond the Standard Model at TeV energies.

Contribution

It introduces a novel analysis of $ riangle L=2$ SMEFT operators at a 2 TeV muon collider, demonstrating its potential to surpass current experimental constraints.

Findings

Sensitivity to eight SMEFT operators at the muon collider.

Potential to improve constraints compared to LHC and FCC projections.

Highlights the collider's capability to probe lepton number violation at TeV scale.

Abstract

We investigate lepton number violation (LNV) induced by $\Delta L = 2$ dimension-seven Standard Model Effective Field Theory (SMEFT) operators in the context of same-sign muon colliders. Specifically, we study $\mu^+ \mu^+ \rightarrow W^+W^+/\;W^+qq'$ production at the $\mu$TRISTAN at $\sqrt{s} =$ 2 TeV with an integrated luminosity of 1 ab$^{-1}$, using the final-state signature comprising two fat jets. This process is sensitive to eight distinct SMEFT operators, providing a unique avenue for testing LNV beyond the Standard Model. We determine the maximal sensitivity to these operators and compare our results with existing LHC constraints and future projections from the FCC. Our findings highlight the potential of same-sign muon colliders to serve as powerful probes of LNV and New Physics (NP) at the TeV scale.