Using a 478 pb⁻¹ data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring at a center-of-mass energy of s√=4.009 GeV, the production of e⁺e⁻→ηJ/ψ is observed for the first time with a statistical significance of greater than 10σ. The Born cross section is measured to be (32.1±2.8±1.3) pb, where the first error is statistical and the second systematic. Assuming the ηJ/ψ signal is from a hadronic transition of the ψ(4040), the fractional transition rate is determined to be B(ψ(4040)→ηJ/ψ)=(5.2±0.5±0.2±0.5)×10⁻³, where the first, second, and third errors are statistical, systematic, and the uncertainty from the ψ(4040) resonant parameters, respectively. The production of e⁺e⁻→π0J/ψ is searched for, but no significant signal is observed, and B(ψ(4040)→π⁰J/ψ)<2.8×10⁻⁴ is obtained at the 90% confidence level.

Ablikim, M.↗

DOE OSTI2012

Measurement of χ cj decaying into pn̄π⁻ and pn̄π⁻π⁰

Using a data sample of 1.06×10⁸ ψ' events collected with the BESIII detector in 2009, the branching fractions of χ cJ →pn̄π⁻ and χ cJ →pn̄π⁻π⁰ (J=0, 1, 2) are measured. (Throughout the text, inclusion of charge conjugate modes is implied if not stated otherwise.) The results for χ c⁰ →pn̄π⁻ and χ c² →pn̄π⁻ are consistent with, but much more precise than, those of previous measurements. The decays of χ c1 →pn̄π⁻ and χ cJ →pn̄π⁻π⁰ are observed for the first time.

Ablikim, M.↗

DOE OSTI2012

Observation of χ cJ decays to ΛΛ¯¯¯π⁺π⁻

Decays of the χ cJ states (J=0, 1, 2) to ΛΛ¯¯¯π⁺π⁻, including processes with intermediate Σ(1385), are studied through the E1 transition ψ'→γχ cJ using 106×10⁶ ψ' events collected with the BESIII detector at BEPCII. This is the first observation of χcJ decays to the final state ΛΛ¯¯¯π⁺π⁻. The branching ratio of the intermediate process χ cJ →Σ(1385) ± Σ¯¯¯(1385) ∓ is also measured for the first time, and the results agree with the theoretical predictions based on the color-octet effect.

Ablikim, M.↗