Search for the radiative transitions ψ(3770)→ γηc and γηc(2S)

Abstract

By using a 2.92 fb-1 data sample taken at √s = 3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions ψ(3770) → γηc and γηc(2S) through the hadronic decays ηc(ηc (2S)) → K0SK±π+. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be B(ψ(3770) →γηc) ±B(ηc → K0SK±π+) < 1.6× 10-5 and B(ψ(3770) →γηc(2S)) ×B(ηc(2S) → K0SK+π+) <5.6× 10-6. Combining our result with world-average values of B(ηc(ηc(2S)) → K0SK±π+), we find the branching fractions B(ψ(3770) → γηc) > 6.8 × 10-4 and B(ψ(3770) → γηc(2S)) < 2.0 × 10-3 at a 90% confidence level.