Measurements of $J/\psi$ and $\psi (2S)$ decays into $\Lambda \bar{\Lambda }{\pi }^0$ and $\Lambda \bar{\Lambda }\eta$

Abstract

Using 58 million $J/\psi$ and 14 million $\psi (2S)$ events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays $J/\psi$ and $\psi (2S)\to \Lambda \bar{\Lambda }{\pi }^0$ and $\Lambda \bar{\Lambda }\eta$ are measured. For the isospin violating decays, the upper limits are determined to be $\mathcal{B}(J/\psi \to \Lambda \bar{\Lambda }{\pi }^0)<6.4\times 10^{-5}$ and $\mathcal{B}(\psi (2S)\to \Lambda \bar{\Lambda }{\pi }^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin conserving process $J/\psi \to \Lambda \bar{\Lambda }\eta$ is observed for the first time, and its branching fraction is measured to be $\mathcal{B}(J/\psi \to \Lambda \bar{\Lambda }\eta )=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the first error is statistical and the second one is systematic. No $\Lambda \bar{\Lambda }\eta$ signal is observed in $\psi (2S)$ decays, and $\mathcal{B}(\psi (2S)\to \Lambda \bar{\Lambda }\eta )<1.2\times 10^{-4}$ is set at the 90% confidence level. Branching fractions of $J/\psi$ decays into ${\Sigma }^{+}{\pi }^{-}bar\Lambda$ and ${\bar{\Sigma }}^{-}{\pi }^{+}\Lambda$ are also reported, and the sum of these branching fractions is determined to be $\mathcal{B}(J/\psi \to {\Sigma }^{+}{\pi }^{-}\bar{\Lambda }+c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$.

arXiv comment7 pages, 10 figures. Phys.Rev.D comments considered

References in corpus (11)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Including Systematic Uncertainties in Confidence Interval Construction for Poisson Statistics
• BESII Detector Simulation
• Measurement of the Branching Fraction of J/psi --> pi+ pi- pi0
• Branching Fraction Measurements of psi(2S) Decay to Baryon-Antibaryon Final States
• Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
• Measurements of psi(2S) decays to octet baryon-antibaryon pairs
• Observation of p pbar pi^0 and p pbar eta in psi' decays
• Measurement of $\psi (2S)$ decays to baryon pairs
• Determination of BR(chi_{cJ} --> p \bar{p}) in psi(2S) decays

Cited by in corpus (3)

• Progress Toward Understanding Baryon Resonances
• First measurements of J/Psi decays into ${\Sigma }^{+}{\bar{\Sigma }}^{-}$ and ${\Xi }^0{\bar{\Xi }}^0$
• Precise measurement of the branching fractions of $J/\psi \to \bar{\Lambda }{\pi }^{+}{\Sigma }^{-}+c.c.$ and $J/\psi \to \bar{\Lambda }{\pi }^{-}{\Sigma }^{+}+c.c.$