SEARCH FOR DECAY MODES OF Ω− IN ψ (2S ) DATA

Abstract

̄ ̄ ̄ A detailed analysis of ψ(2S) → Ω− Ω+ ( Ω− → ΛK − , Λ → pπ − , Ω+ → ΛK + and ̄ Λ → pπ + ) decay channel has been undertaken in this work. About 14 million ψ(2S) ̄ decays recorded by Beijing Spectrometer II (BESII) at Beijing Electron Positron ̄ Collider (BEPC), have been used. In earlier measurements of ψ(2S) → Ω− Ω+ , no ̄ significant signal of Ω− or Ω+ was found. Through a new technique of selecting ̄ events with one missing charge track also, we report a first evidence of Ω− and Ω+ signals with statistical significance levels of 5.3 σ and 4.6 σ, respectively. A branching ̄ fraction of ψ(2S) → Ω− Ω+ has been determined to be (3.21 ± 1.25 ± 0.97) × 10−5 . The errors are statistical and systematic, respectively.