Baryon/Lepton number violation searches at BESIII

Abstract

Based on 2.93 fb − 1 of 𝑒 + 𝑒 − collision data taken at √ 𝑠 = 3 . 773 GeV and 1.31 × 10 9 𝐽 / 𝜓 events taken at √ 𝑠 = 3 . 097 GeV, we present the searches for baryon number and lepton number violation in 𝐷 0 → 𝑝𝑒 − ( ¯ 𝑝𝑒 + ) , 𝐷 + → ¯ Λ ( ¯ Σ 0 ) 𝑒 + , 𝐷 + → Λ ( Σ 0 ) 𝑒 + , 𝐷 ± → 𝑛 ( ¯ 𝑛 ) 𝑒 ± , 𝐽 / 𝜓 → Λ + 𝑐 𝑒 − + 𝑐.𝑐 , and 𝐽 / 𝜓 → 𝑝𝐾 − ¯ Λ + 𝑐.𝑐 decays. No obvious signals are found and the upper limits on the branching fractions of these decays are set to be ∼ 10 − 8 − 10 − 6 at 90% confidence level. Those results are the most stringent ones to date for these processes but are still far above the prediction of the higher generation model.