We present an analysis of the process ψ(3686)→Ω^{-}Ωover ¯^{+} (Ω^{-}→K^{-}Λ, Ωover ¯^{+}→K^{+}Λover ¯, Λ→pπ^{-}, Λover ¯→pover ¯π^{+}) based on a dataset of 448×10^{6} ψ(3686) decays collected with ...the BESIII detector at the BEPCII electron-positron collider. The helicity amplitudes for the process ψ(3686)→Ω^{-}Ωover ¯^{+} and the decay parameters of the subsequent decay Ω^{-}→K^{-}Λ (Ωover ¯^{+}→K^{+}Λover ¯) are measured for the first time by a fit to the angular distribution of the complete decay chain, and the spin of the Ω^{-} is determined to be 3/2 for the first time since its discovery more than 50 years ago.
The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the ...capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here.
We report a branching fraction measurement of the singly Cabibbo-suppressed decay Λ+c → ΛK+ using a data sample collected with the BESIII detector at the BEPCII storage ring. The data span ...center-of-mass energies from 4.599 to 4.950 GeV and correspond to an integrated luminosity of 6.44 fb −1 . The branching fraction of Λ+c → ΛK+ relative to that of the Cabibbo-favored decay Λ+c → Λπ+ is measured to be R = B(Λ+c → ΛK+) / B(Λ+c → Λπ+) = (4.78±0.34±0.20)%. Combining with the world-average value of B(Λ+c → Λπ+), we obtain B(Λ+c → ΛK+) = (6.21±0.44±0.26±0.34) × 10 −4 . Here the first uncertainties are statistical, the second systematic, and the third comes from the uncertainty of the Λ+c→Λπ+ branching fraction. This result, which is more precise than previous measurements, does not agree with theoretical predictions, and suggests that nonfactorizable contributions have been underestimated in current models.
AIMS: Wheat straw is generated in billions of tons around the world every year and has not been fully used. This study sought to evaluate the delignification capacity and enzyme production of ...Trametes trogii MT strain and to clarify the changes of structure and chemical composition of wheat straw during the decay process. METHODS AND RESULTS: The results obtained revealed that the T. trogii MT strain has the ability to degrade lignin, cellulose as well as hemicellulose of wheat straw simultaneously. The strain can produce high activities of laccase, manganese peroxidase, xylanase, carboxymethylcellulase and feruloyl esterase but no lignin peroxidases during the decay process of a 60‐day incubation period on wheat straw. Scanning electron microscopy observation and infrared spectroscopy analysis showed the lignin and carbohydrate of wheat straw were degraded with no obvious different levels. The low molecular mass fractions collected from the culture of the MT strains grown in wheat straw powder liquid medium showed high Fe³⁺chelating, reducing capacity and hydroxyl radical and hydrogen peroxide generation. CONCLUSIONS: Trametes trogii MT has a complex mechanism to degrade lignocellulose, in addition to the extracellular enzymatic systems, and has great potential as an attractive micro‐organism used for the biological degradation of waste straws. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed the dynamic changes of the ligninolytic enzymes of T. trogii MT during the degradation of wheat straw, and suggested that the decay patterns of wheat straw by T. trogii MT had some simultaneous type characteristics.
Using (10 087±44)×10^{6} J/ψ events collected with the BESIII detector, the radiative hyperon decay Σ^{+}→pγ is studied at an electron-positron collider experiment for the first time. The absolute ...branching fraction is measured to be (0.996±0.021_{stat}±0.018_{syst})×10^{-3}, which is lower than its world average value by 4.2 standard deviations. Its decay asymmetry parameter is determined to be -0.652±0.056_{stat}±0.020_{syst}. The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by 78% and 34%, respectively.
PDF
