First measurements of the decays of the three χcJ states to pp̄K⁺K⁻ final states are presented. Intermediate Φ→K⁺K⁻ and Λ(1520)→pK⁻ resonance states are observed, and branching fractions for ...χcJ→p̄K⁺Λ(1520), Λ(1520)Λ¯¯¯(1520), and Φpp̄ are reported. We also measure branching fractions for direct χcJ→pp̄K⁺K⁻ decays. These are first observations of χcJ decays to unstable baryon resonances and provide useful information about the χcJ states. The experiment uses samples of χcJ mesons produced via radiative transitions from 106×10⁶ ψ' mesons collected in the BESIII detector at the BEPCII e⁺e⁻ collider.
Observation of χ c J decays to Λ Λ ¯ π + π Ablikim, M.; Bertani, M.; Bondarenko, O. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
9/2012, Volume:
86, Issue:
5
Journal Article
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.
We report the first absolute measurement of the branching fraction of \(\Lambda^+_{c}\rightarrow \Lambda e^+\nu_e\). This measurement is based on 567 pb\(^{-1}\) of \(e^+e^-\) annihilation data ...produced at \(\sqrt{s}=4.599\) GeV, which is just above the \(\Lambda^+_c\bar{\Lambda}^-_c\) threshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be \(\mathcal B({\Lambda^+_c\rightarrow \Lambda e^+\nu_e})=(3.63\pm0.38({\rm stat})\pm0.20({\rm syst}))\%\), representing a more than twofold improvement in precision upon previously published results. As the branching fraction for \(\Lambda^+_{c}\rightarrow \Lambda e^+\nu_e\) is the benchmark for those of other \(\Lambda^+_c\) semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.
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