Measurement of psi(3686) -> Lambda(Lambda)over-bar eta and psi(3686) -> Lambda(Lambda)over-bar pi(0) decays

• Based on a sample of 448.1 x 10(6) psi(3686) events collected with the BESIII detector, a study of psi(3686) -> Lambda(Lambda) over bar pi(0) and psi(3686) -> Lambda(Lambda) over bar eta is performed. Evidence of the isospin-violating decay psi(3686) -> Lambda(Lambda) over bar pi(0) is found for the first time with a statistical significance of 3.7 sigma, the branching fraction B(psi(3686) -> Lambda(Lambda) over bar pi(0)) is measured to be (1.42 +/- 0.39 +/- 0.59) x 10(-6), and its corresponding upper limit is determined to be 2.47 x 10(-6) at 90% confidence level. A partial wave analysis of psi(3686) -> Lambda(Lambda) over bar eta shows that the peak around Lambda eta invariant mass threshold favors a Lambda* resonance with mass and width in agreement with the Lambda(1670). The branching fraction of the psi(3686) -> Lambda(Lambda) over bar eta is measured to be (2.34 +/- 0.18 +/- 0.52) x 10(-5). The first uncertainties are statistical and the second are systematic.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

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