Isospin violating decays of vector charmonia.

We study the isospin violating decays of vector charmonia to Λ Σ ¯ 0 and its charge conjugate. They are dominated by the single photon annihilation and can be evaluated reliably with timelike form factors. We utilize the quark-pair creation model, which is valid for the OZI suppressed decays, to evaluate the form factors. We obtain the branching fractions of B (J / ψ → Λ Σ ¯ 0 + c. c.) = (2.4 ± 0.4) × 10 - 5 and B (ψ (2 S) → Λ Σ ¯ 0 + c. c.) = (3.0 ± 0.5) × 10 - 6 , which are compatible with the measurements by the BESIII collaborations, respectively. The decay asymmetries are found to be α J / ψ = 0.314 and α ψ (2 S) = 0.461 , which can be examined at BESIII in the foreseeable future. [ABSTRACT FROM AUTHOR]