26 research outputs found

    Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

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    Determination of the number of J/ψ events with inclusive J/ψ decays

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    A measurement of the number of J/ψ events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be (223.7 ± 1.4) × 106, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/ψ events taken in 2012 is determined to be (1086.9 ± 6.0) × 106. In total, the number of J/ψ events collected with the BESIII detector is measured to be (1310.6 ± 7.0) × 106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible

    Measurement of the branching fraction for ψ(3770)→γχc0

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    By analyzing a data set of 2.92 fb−1 of e+e− collision data taken at s=3.773 GeV and 106.41×106 ψ(3686) decays taken at s=3.686 GeV with the BESIII detector at the BEPCII collider, we measure the branching fraction and the partial decay width for ψ(3770)→γχc0 to be B(ψ(3770)→γχc0)=(6.88±0.28±0.67)×10−3 and Γ[ψ(3770)→γχc0]=(187±8±19) keV, respectively. These are the most precise measurements to date

    Amplitude Analysis of the Decays η′ →π+π-π0 and η′ →π0π0π0

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    Based on a sample of 1.31×109 J/ψ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays η′→π+π-π0 and η′→π0π0π0 is performed. A significant P-wave contribution from η′→ρ±π is observed for the first time in η′→π+π-π0. The branching fraction is determined to be B(η′→ρ±π)=(7.44±0.60±1.26±1.84)×10-4, where the first uncertainty is statistical, the second systematic, and the third model dependent. In addition to the nonresonant S-wave component, there is a significant σ meson component. The branching fractions of the combined S-wave components are determined to be B(η′→π+π-π0)S=(37.63±0.77±2.22±4.48)×10-4 and B(η′→π0π0π0)=(35.22±0.82±2.54)×10-4, respectively. The latter one is consistent with previous BESIII measurements

    Study of ψ decays to the Ξ- Ξ + and Σ (1385)a Σ (1385)± final states STUDY of ψ

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    We study the decays of the charmonium resonances J/ψ and ψ(3686) to the final states Ξ-Ξ+, Σ(1385) Σ(1385)± based on a single baryon tag method using data samples of (223.7±1.4)×106 J/ψ and (106.4±0.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. The decay ψ(3686)→Σ(1385) Σ(1385)± is observed for the first time, and the measurements of the other processes, including the branching fractions and angular distributions, are in good agreement with, and much more precise than, the previously published results. Additionally, the ratios B(ψ(3686)→Ξ-Ξ+)B(J/ψ→Ξ-Ξ+), B(ψ(3686)→Σ(1385)-Σ(1385)+)B(J/ψ→Σ(1385)-Σ(1385)+) and B(ψ(3686)→Σ(1385)+Σ(1385)-)B(J/ψ→Σ(1385)+Σ(1385)-) are determined
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