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Based on (2712. 4 14. 3) 10^6 e^+e^- (3686) events collected with the BESIII detector operating at the BEPCII collider, we report the first evidence of ₂₀ decays and the first observation of ₂₁, ₂ decays, with significances of 4. 5, 11. 3 and 13. 0, respectively. The decay branching fractions of ₂₀, ₁, ₂ are measured to be (2. 991. 240. 19) 10^-5, (6. 010. 900. 40) 10^-5, and (7. 130. 810. 36) 10^-5, where the first uncertainties are statistical and the second systematic. No obvious enhancement near the production threshold or excited state is found in the (or) system.
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