Search for Λ- Λ ¯ oscillation in J/ψ → Λ Λ ¯ decay

Using (10087±44)×106 J/ψ decays collected by the BESIII detector at the BEPCII collider, we search for baryon number violation via Λ-Λ¯ oscillation in the decay J/ψ→ΛΛ¯. No evidence for Λ-Λ¯ oscillation is observed. The upper limit on the time-integrated probability of Λ-Λ¯ oscillation is estimated to be 1.4×10-6, corresponding to an oscillation parameter less than 2.1×10-18 GeV at 90% confidence level.