Measurements of $J/ψ$ and $ψ(2S)$ decays into $Λ\barΛπ^0$ and $Λ\barΛη$
Abstract
Description
Using 58 million $J/ψ$ and 14 million $ψ(2S)$ events collected by the BESII detector at the BEPC, branching fractions or upper limits for the decays $J/ψ$ and $ψ(2S) \to Λ\barΛπ^0$ and $Λ\barΛη$ are measured. For the isospin violating decays, the upper limits are determined to be ${\cal B}(J/ψ\to Λ\barΛπ^0)<6.4\times 10^{-5}$ and ${\cal B}(ψ(2S) \to Λ\barΛπ^0)<4.9\times 10^{-5}$ at the 90% confidence level. The isospin conserving process $J/ψ\to Λ\barΛη$ is observed for the first time, and its branching fraction is measured to be ${\cal B}(J/ψ\to Λ\barΛη)=(2.62\pm 0.60\pm 0.44)\times 10^{-4}$, where the first error is statistical and the second one is systematic. No $Λ\barΛη$ signal is observed in $ψ(2S)$ decays, and ${\cal B}(ψ(2S) \to Λ\barΛη)<1.2\times 10^{-4}$ is set at the 90% confidence level. Branching fractions of $J/ψ$ decays into $Σ^+ π^- barΛ$ and $\barΣ^- π^+ Λ$ are also reported, and the sum of these branching fractions is determined to be ${\cal B}(J/ψ\to Σ^+π^- \barΛ + c.c.)=(1.52\pm 0.08\pm 0.16)\times 10^{-3}$.
7 pages, 10 figures. Phys.Rev.D comments considered
7 pages, 10 figures. Phys.Rev.D comments considered