Study of A — A oscillation in quantum coherent AA by using J/ψ → ΛΛ̄ decay

We discuss the possibility of searching for the Λ — Λ oscillations for coherent ΛΛ production in the J/ψ → ΛΛ decay process. The sensitivity of measurement of A — A oscillation in the external field at BES-III experiment is considered. These considerations indicate an alternative way to probe the ΔB = 2 amplitude in addition to neutron oscillation experiments. Both coherent and time-dependent information can be used to extract the Λ - Λ oscillation parameter. With one year's luminosity at BES-III, we can set an upper limit of δm ΛΛ < 10 -15 MeV at 90% confidence level, corresponding to about 10 -6 s of A — A oscillation time.