Search for the lepton number violation decay ω→π⁺π⁺e⁻e⁻+c.c.

Lepton number violation decay ω → π⁺π⁺e⁻e⁻ + c.c. is searched for via J/ψ → ωη using a data sample of (1.0087 ± 0.0044) × 10¹⁰ J/ψ events collected via the BESIII detector at the BEPCII collider. No significant signal is observed, and the upper limit on the branching fraction of ω → π⁺π⁺e⁻e⁻ + c.c. at the 90% confidence level is determined for the first time to be 2.8 × 10⁻⁶.