Ch F Redmer

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Based on a sample of 1.31×10^{9}  J/ψ events collected with the BESIII detector, an amplitude analysis of the isospin-violating decays η^{'}→π^{+}π^{-}π^{0} and η^{'}→π^{0}π^{0}π^{0} is performed. A significant P-wave contribution from η^{'}→ρ^{±}π^{∓} is observed for the first time in η^{'}→π^{+}π^{-}π^{0}. The branching fraction is determined to be(More)
We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process e^{+}e^{-}→ππX, based on a data set of 62  pb^{-1} at the center-of-mass energy of 3.65 GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with(More)
a r t i c l e i n f o a b s t r a c t We extract the e + e − → π + π − cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb −1 taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is(More)
Using 1.09×10^{9} J/ψ events collected by the BESIII experiment in 2012, we study the J/ψ→γη^{'}π^{+}π^{-} process and observe a significant abrupt change in the slope of the η^{'}π^{+}π^{-} invariant mass distribution at the proton-antiproton (pp[over ¯]) mass threshold. We use two models to characterize the η^{'}π^{+}π^{-} line shape around 1.85 (More)
An improved limit for ee of X(3872) and ee measurement of ψ(3686) a r t i c l e i n f o a b s t r a c t ψ(3686) ee Charmonium spectroscopy BESIII Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction e + e − → γ ISR X(3872) → γ ISR π + π − J /ψ via the Initial State(More)
Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of sqrt[s]=4.23, 4.26, and 4.36 GeV, we observe e(+)e(-)→π(0)π(0)hc for the first time. The Born cross sections are measured and found to be about half of those of e(+)e(-)→π(+)π(-)hc within less than 2σ. In the π(0)hc mass spectrum,(More)
Studies of η meson decays with the WASA detector are a major goal of the experimental program at COSY-Jülich. In 2008 a sample of 10 7 η mesons was collected in pd → 3 He η reaction close to threshold without trigger bias on the decay channels. The status of the analysis of various decay channels is presented. Studies of η meson decays with WASA A. Kupsc(More)