Probing the Weinberg Operator at Colliders

Motivated by searches for 0νββ decay in nuclear experiments and collider probes of lepton number violation at dimension d≥7, we investigate the sensitivity to the d=5 Weinberg operator using the nonresonant signature pp→ℓ±ℓ′±jj at the LHC. We develop a prescription for the operator that is applicable in collisions and decays, and focus on the ℓℓ′=μμ channel, which is beyond the reach of nuclear decays. For a Wilson coefficient C5μμ=1, scales as heavy as Λ∼8.3(11) TeV can be probed with L=300 fb-1(3 ab-1). This translates to an effective μμ Majorana mass of |mμμ|∼7.3(5.4) GeV and establishes a road map for testing the Weinberg operator at accelerators.