Measurement of ψ (3686) → Λ Λ ¯ η and ψ (3686) → Λ Λ ¯ π0 decays

Based on a sample of 448.1×106ψ(3686) events collected with the BESIII detector, a study of ψ(3686)→ΛΛ¯π0 and ψ(3686)→ΛΛ¯η is performed. Evidence of the isospin-violating decay ψ(3686)→ΛΛ¯π0 is found for the first time with a statistical significance of 3.7σ, the branching fraction B(ψ(3686)→ΛΛ¯π0) is measured to be (1.42±0.39±0.59)×10-6, and its corresponding upper limit is determined to be 2.47×10-6 at 90% confidence level. A partial wave analysis of ψ(3686)→ΛΛ¯η shows that the peak around Λη invariant mass threshold favors a Λ∗ resonance with mass and width in agreement with the Λ(1670). The branching fraction of the ψ(3686)→ΛΛ¯η is measured to be (2.34±0.18±0.52)×10-5. The first uncertainties are statistical and the second are systematic