Observation of the J /ψ and ψ (3686) decays into η ς+ ς ¯ -

Abstract

The decays J/ψ→ης+ς¯- and ψ(3686)→ης+ς¯- are observed for the first time, using (10087±44)×106 J/ψ and (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. We determine the branching fractions of these two decays to be B(J/ψ→ης+ς¯-)=(6.34±0.21±0.37)×10-5 and B(ψ(3686)→ης+ς¯-)=(9.59±2.37±0.61)×10-6, where the first uncertainties are statistical and the second are systematic. The ratio of these two branching fractions is determined to be B(ψ(3686)→ης+ς¯-)B(J/ψ→ης+ς¯-)=(15.1±3.8)%, which is in agreement with the "12% rule."