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Senecio inaequidens DC., eine in Mitteleuropa bislang nur von Ruderalstandorten bekannte Art, hat sich neuerdings auf den Ostfriesischen Inseln als fester Bestandteil der natürlichen Dünenvegetation (Elymo-Ammophiletum, Hippophao-Salicetum arenariae)etabliert und sich dort vom Epökophyten zum Agriophyten gewandelt. Auf entsprechenden Standorten wurde die Art bislang auf Borkum, Baltrum, Spiekeroog, Wangerooge, Oldeoog und Mellum gefunden.
By analyzing the large-angle Bhabha scattering events e+e− → (γ)e+e− and diphoton events e+e− → (γ)γγ for the data sets collected at center-of-mass (c.m.) energies between 2.2324 and 4.5900 GeV (131 energy points in total) with the upgraded Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider (BEPCII), the integrated luminosities have been measured at the different c.m. energies, individually. The results are important inputs for the R value and J/ψ resonance parameter measurements.
To study the nature of the state Y (2175), a dedicated data set of e+e− collision data was collected at the center-of-mass energy of 2.125 GeV with the BESIII detector at the BEPCII collider. By analyzing large-angle Bhabha scattering events, the integrated luminosity of this data set is determined to be 108.49±0.02±0.85 pb−1, where the first uncertainty is statistical and the second one is systematic. In addition, the center-of-mass energy of the data set is determined with radiative dimuon events to be 2126.55±0.03±0.85 MeV, where the first uncertainty is statistical and the second one is systematic.
The decays of χc2→K+K−π0, KSK±π∓ and π+π−π0 are studied with the ψ(3686) data samples collected with the Beijing Spectrometer (BESIII). For the first time, the branching fractions of χc2→K∗K¯¯¯¯¯, χc2→a±2(1320)π∓/a02(1320)π0 and χc2→ρ(770)±π∓ are measured. Here K∗K¯¯¯¯¯ denotes both K∗±K∓ and K∗0K¯¯¯¯¯0+c.c., and K∗ denotes the resonances K∗(892), K∗2(1430) and K∗3(1780). The observations indicate a strong violation of the helicity selection rule in χc2 decays into vector and pseudoscalar meson pairs. The measured branching fractions of χc2→K∗(892)K¯¯¯¯¯ are more than 10 times larger than the upper limit of χc2→ρ(770)±π∓, which is so far the first direct observation of a significant U-spin symmetry breaking effect in charmonium decays.
Using a data sample of 448.1×106 𝜓(3686) events collected with the BESIII detector operating at the BEPCII, we perform search for the hadronic transition ℎ𝑐→𝜋+𝜋−𝐽/𝜓 via 𝜓(3686)→𝜋0ℎ𝑐. No signals of the transition are observed, and the upper limit on the product branching fraction ℬ(𝜓(3686)→𝜋0ℎ𝑐)ℬ(ℎ𝑐→𝜋+𝜋−𝐽/𝜓) at the 90% confidence level (C.L.) is determined to be 2.0×10−6. This is the most stringent upper limit to date.
The decay 𝐽/𝜓→𝛾𝛾𝜙 is studied using a sample of 1.31×109 𝐽/𝜓 events collected with the BESIII detector. Two structures around 1475 MeV/𝑐2 and 1835 MeV/𝑐2 are observed in the 𝛾𝜙 invariant mass spectrum for the first time. With a fit on the 𝛾𝜙 invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around 1475 MeV/𝑐2 is found to favor an assignment as the 𝜂(1475) and the mass and width for the structure around 1835 MeV/𝑐2 are consistent with the 𝑋(1835). The statistical significances of the two structures are 13.5𝜎 and 6.3𝜎, respectively. The results indicate that both 𝜂(1475) and 𝑋(1835) contain a sizeable 𝑠¯𝑠 component.
Using a low background data sample of 9.7×105 𝐽/𝜓→𝛾𝜂′, 𝜂′→𝛾𝜋+𝜋− events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII detector at BEPCII, the decay dynamics of 𝜂′→𝛾𝜋+𝜋− are studied with both model-dependent and model-independent approaches. The contributions of 𝜔 and the 𝜌(770)−𝜔 interference are observed for the first time in the decays 𝜂′→𝛾𝜋+𝜋− in both approaches. Additionally, a contribution from the box anomaly or the 𝜌(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.
Measurements of the branching fractions for D⁺ → Kₛ⁰Kₛ⁰K⁺, Kₛ⁰Kₛ⁰π⁺ and D⁰ → Kₛ⁰Kₛ⁰, Kₛ⁰Kₛ⁰Kₛ⁰
(2016)
By analyzing 2.93 fb−1 of data taken at the ψ(3770) resonance peak with the BESIII detector, we measure the branching fractions for the hadronic decays D+→K0SK0SK+, D+→K0SK0Sπ+, D0→K0SK0S and D0→K0SK0SK0S. They are determined to be B(D+→K0SK0SK+)=(2.54±0.05stat.±0.12sys.)×10−3, B(D+→K0SK0Sπ+)=(2.70±0.05stat.±0.12sys.)×10−3, B(D0→K0SK0S)=(1.67±0.11stat.±0.11sys.)×10−4 and B(D0→K0SK0SK0S)=(7.21±0.33stat.±0.44sys.)×10−4, where the second one is measured for the first time and the others are measured with significantly improved precision over the previous measurements.
Measurements of the branching fractions for D⁺ → Kₛ⁰Kₛ⁰K⁺, Kₛ⁰Kₛ⁰π⁺ and D⁰ → Kₛ⁰Kₛ⁰, Kₛ⁰Kₛ⁰Kₛ⁰
(2016)
By analyzing 2.93 fb−1 of data taken at the ψ(3770) resonance peak with the BESIII detector, we measure the branching fractions for the hadronic decays D+→K0SK0SK+, D+→K0SK0Sπ+, D0→K0SK0S and D0→K0SK0SK0S. They are determined to be B(D+→K0SK0SK+)=(2.54±0.05stat.±0.12sys.)×10−3, B(D+→K0SK0Sπ+)=(2.70±0.05stat.±0.12sys.)×10−3, B(D0→K0SK0S)=(1.67±0.11stat.±0.11sys.)×10−4 and B(D0→K0SK0SK0S)=(7.21±0.33stat.±0.44sys.)×10−4, where the second one is measured for the first time and the others are measured with significantly improved precision over the previous measurements.
We study the decays of J/ψ and ψ(3686) to the final states Σ(1385)0Σ¯(1385)0 and Ξ0Ξ¯0 based on a single baryon tag method using data samples of (1310.6±7.0)×106 J/ψ and (447.9±2.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. The decays to Σ(1385)0Σ¯(1385)0 are observed for the first time. The measured branching fractions of J/ψ and ψ(3686)→Ξ0Ξ¯0 are in good agreement with, and much more precise, than the previously published results. The angular parameters for these decays are also measured for the first time. The measured angular decay parameter for J/ψ→Σ(1385)0Σ¯(1385)0, α=−0.64±0.03±0.10, is found to be negative, different to the other decay processes in this measurement. In addition, the "12\% rule" and isospin symmetry in the J/ψ and ψ(3686)→ΞΞ¯ and Σ(1385)Σ¯(1385) systems are tested.
