Abstract:
Using 14 million ψ(2S) decay events registered by Beijing Spectrometer II commonly
known as BESII at Beijing Electron Positron Collider (BEPC), we have performed
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detailed study of ψ(2S) → ΛΛKs (a strangeness and isospin violating process), to
look for any hint beyond the ’Standard Model’. Finding no obvious signal, we report,
first time, an upper limit of 9.3 × 10−5 at 90% confidence level, for the branching
fraction.
