6533b855fe1ef96bd12b0683

RESEARCH PRODUCT

Measurements of the branching fractions forJ/ψandψ′→ΛΛ¯π0andΛΛ¯η

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We report on a study of the isospin-violating and isospin-conserving decays of the J/psi and psi' charmonium state to Lambda(Lambda) over bar pi(0) and Lambda(Lambda) over bar eta, respectively. The data are based on 225 million J/psi and 106 million psi' events that were collected with the BESIII detector. The most accurate measurement of the branching fraction of the isospin-violating process J/psi -> Lambda(Lambda) over bar pi(0) is obtained, and the isospin-conserving processes J/psi -> Lambda(Lambda) over bar eta and psi' -> Lambda(Lambda) over bar eta are observed for the first time. The branching fractions are measured to be B(J/psi -> Lambda(Lambda) over bar pi(0)) = (3.78 +/- 0.27(stat) +/- 0.30(sys)) x 10(-5), B(J/psi -> Lambda(Lambda) over bar eta) = (15.7 +/- 0.80(stat) +/- 1.54(sys)) x 10(-5) and B(psi' -> Lambda(Lambda) over bar eta) = (2.48 +/- 0.34(stat) +/- 0.19(sys)) x 10(-5). No significant signal events are observed for psi' -> Lambda(Lambda) over bar pi(0) decay resulting in an upper limit of the branching fraction of B(psi' -> Lambda(Lambda) over bar pi(0)) Sigma(1385)(0) + c.c. is searched for, and the upper limit is B(J/psi -> Sigma(1385)(0)(Lambda) over bar + c.c.) <0.82 x 10(-5) at the 90% confidence level. DOI: 10.1103/PhysRevD.87.052007